Software

Web browsers

www.mozilla.org - browsers you can find here:
Mozilla Firefox (9/10) - web browser with MDI interface (read tabbed browsing in this case) and more, it's updated quite often,
Mozilla suite and the Seamonkey project (10/10) - web browser, e-mail client, chat program, html editor.
There is also a list of other projects using the Gecko engine, including browsers for only a single platform.
Check out addons.mozilla.org for add-ons. These browsers feature excellent standards compliance (to be more precise, their engine does).
Available for: Windows | Linux | Mac | Other systems

Opera - a great web browser (10/10), small, now all free =D, has a tabbed (MDI) interface , supports mouse gestures. Integrated e-mail client and other stuff. Excellent standards compliance.
Available for: Windows | Linux | Mac | Other systems

K-Meleon - made for Windows only, it therefore has bit faster interface than Firefox, uses Gecko (like Mozilla suite / Mozilla Firefox / Netscape). A good bet for slower PCs and older versions of Windows (95/98). Nicely customizable.
Available for: Windows | Linux | Mac | Other systems

www.netscape.com - you'll find here (among other things) Netscape (8/10), an Internet suite like Mozilla suite, since version 8 based on Firefox and requiring IE as well.
Available for: Windows | Linux | Mac | Other systems

www.microsoft.com - for those who have OS Windows and a faster Internet connection: Internet Explorer (7/10).
Available for: Windows | Linux | Mac | Other systems

www.avantbrowser.com, Maxthon - These two browsers are very similar Internet Explorer (IE) enhancements. Using these you can control what you download, skinnable, MDI. Lots of helpful stuff in these. Need IE.
Available for: Windows | Linux | Mac | Other systems

WEB - very small but otherwise useful web browser (browsing only, no page saving on your disk).
Available for: Windows | Linux | Mac | Other systems

E-mail clients

Thunderbird - a nice e-mail client that offers adaptive junkmail control. Supports POP3, IMAP, SMTP, ...
Available for: Windows | Linux | Mac | Other systems

Sylpheed - a lightweight and simple e-mail client that offers junkmail filtering. Supports POP3, IMAP, SMTP, ...
Available for: Windows | Linux | Mac | Other systems

Pegasus Mail - an e-mail client that is almost too feature-rich, it's user interface looks a bit cluttered, but one can get used to it. Supports POP3, IMAP, SMTP, ...
Available for: Windows | Linux | Mac | Other systems

Y.A.M.C.! - a small and fast e-mail client. Supports POP3, IMAP, SMTP, ...
Available for: Windows | Linux | Mac | Other systems

IncrediMail - looks great, works fine, feels a bit bulky, the free version is somewhat limited but still usable. Supports POP3, SMTP, ...
Available for: Windows | Linux | Mac | Other systems

Foxmail - a chinese e-mail client. Supports english locale as well. Supports POP3, IMAP, ...
Available for: Windows | Linux | Mac | Other systems

Instant messengers

Gaim - supports loads of IM protocols, including MSN, AOL, ICQ, Yahoo, IRC, ....
Available for: Windows | Linux | Mac | Other systems

Miranda - a lightweight IM client that supports MSN, AOL, ICQ, Yahoo, IRC etc.
Available for: Windows | Linux | Mac | Other systems

Easy Message - a very simple but still quite usable IM client supporting MSN, AOL, ICQ, and Yahoo.
Available for: Windows | Linux | Mac | Other systems

File transfer

Download Managers:

http://www.freedownloadmanager.org/ - download manager, 9/10, IE, Firefox - without downloading an add-on.
Available for: Windows | Linux | Mac | Other systems

www.getright.com - also a very good download manager, 9/10, for IE, after installation of a downloaded patch also for Netscape, Mozilla, Opera.
Available for: Windows | Linux | Mac | Other systems

www.amazesoft.com - here's a pretty good download manager FlashGet (9/10), shareware with a banner now.
Available for: Windows | Linux | Mac | Other systems

FTP:

FileZilla - free, fast, customizable.
Available for: Windows | Linux | Mac | Other systems

Bittorrent:

http://www.bitcomet.com/ - fast, easy to setup, nice options.
Available for: Windows | Linux | Mac | Other systems

Antivirus

www.alwil.com - this one has been quite good in the past few month. It is a bit slower, but it's free for home non-commercial use. I've chosen this one according to its results in Virus Bulletin tests.
Available for: Windows | Linux | Mac | Other systems

Firewalls

Comodo Firewall Pro - a free, easy to use and effective personal firewall.
Available for: Windows | Linux | Mac | Other systems

Other very good firewalls are Zone Alarm free for non-commercial / home use.
Available for: Windows | Linux | Mac | Other systems

2D Graphics

Superb freeware tool for creating and editing images (pictures): The Gimp (Czech & Slovak website of the GIMP).
Available for: Windows | Linux | Mac | Other systems

My GIMP plug-in pack binary plug-ins for Windows + some scripts. All of the plug-ins can be found on GIMP Plug-In Registry, this is just a collection I find handy :).

These are some of the good freeware ones:
Paint.NET - is GIMP too complex for your needs? Try this one.
Available for: Windows | Linux | Mac | Other systems

Serif PhotoPlus - not bad, but slow.
Available for: Windows | Linux | Mac | Other systems

Pixia - speedy and rather simple, it's more a painting program than an editor,
Available for: Windows | Linux | Mac | Other systems

Free digital camera raw converters:
RawTherapee - maybe the best free raw converter around at the moment.
Available for: Windows | Linux | Mac | Other systems

UFRaw - this one's pretty neat as well.
Available for: Windows | Linux | Mac | Other systems

dcraw - command line only, but it's OK for batch processing. For a tutorial, head here.
Available for: Windows | Linux | Mac | Other systems

RAWHide - it's in its fairly early stages, but it might work well for you already.
Available for: Windows | Linux | Mac | Other systems

s7raw - made for Fuji cameras, it' a decent tool and one worth having a look at if you're a Fuji owner.
Available for: Windows | Linux | Mac | Other systems


Don't forget there are often usable tools made for the camera you have by its manufacturer. Canon has DPP, Nikon has ViewNX, the others have some too (some brands ship cameras with a version of SILKYPIX Developer Studio).

Vector graphics tools for free: Inkscape - a good one to start with
Available for: Windows | Linux | Mac | Other systems

another nice one is ZonerDraw, not too stable but not too bad either.
Available for: Windows | Linux | Mac | Other systems

BIMP Lite - batch image manipulation - resize, convert, apply built-in effects.
Available for: Windows | Linux | Mac | Other systems

Multiple Image Resizer .NET - yes it does use the .NET framework but is speedy indeed and quality of the shrunk images can be pretty good (especially when bicubic method is applied).
Available for: Windows | Linux | Mac | Other systems

Image Converter Lite - a good free image converter, easy to use, plenty of image formats to use.
Available for: Windows | Linux | Mac | Other systems

PNGGauntlet - a PNG compressor, works really well and is easy to use.
Available for: Windows | Linux | Mac | Other systems

3D Graphics

Blender - splendid stuff. Just a bit unusual environment. Check the tutorials.
Available for: Windows | Linux | Mac | Other systems

Terragen - "Terragen is a work-in-progress scenery generator for Windows and the Mac OS. At this stage of its development, Terragen is free for personal non-commercial use." The results are not bad.
Available for: Windows | Linux | Mac | Other systems

Image viewers

FuturixImager - fast, free, simple, extensible;
Available for: Windows | Linux | Mac | Other systems

IrfanView - very fast, mean and lean program free for non-commercial use;
Available for: Windows | Linux | Mac | Other systems

XnView - supports a huge amount of file formats, free for non-commercial use;
Available for: Windows | Linux | Mac | Other systems

Picasa - more than a nice image manager - a good looking piece of freeware.
Available for: Windows | Linux | Mac | Other systems

F-Spot - is a personal photo management application for the GNOME desktop. It's easy to use and simple, yet enough for many.
Available for: Windows | Linux | Mac | Other systems

iBrowser;
Available for: Windows | Linux | Mac | Other systems

P3dO Explorer;
Available for: Windows | Linux | Mac | Other systems

Audio / video

Codec packs:

Free codecs packs

Players:

Media Player Classic - has the looks of Windows Media Player 6, but it's far more functional. Packed with e. g. K-Lite Mega Codec Pack. Plays everything you install a codec for ;-).
Available for: Windows | Linux | Mac | Other systems

VLC media player - comes bundled with pretty much all the codecs you'll need - they're codecs only for itself, though. It doesn't litter the registry like codec packs tend to.
Available for: Windows | Linux | Mac | Other systems

VLC media player - it has most of the codecs you'll need built right into the player, so you probably won't have to download any codecs if you'll go for this one. It doesn't litter the registry like codec packs tend to.
Available for: Windows | Linux | Mac | Other systems

If you pair this one with xvid, it's quite nice for screen capture: CamStudio.
Available for: Windows | Linux | Mac | Other systems

A nice tool for making instruction videos: Wink.
Available for: Windows | Linux | Mac | Other systems

Compression

If you are interested in file compressing software click here - There is a chart and some information which you may find useful.

CD burners

CheetahBurner.com - Nice, cheap, good (9/10). Shareware, unfortunately.
Available for: Windows | Linux | Mac | Other systems

InfraRecorder - easy to use, works pretty well. There's also a portable version available on its website.
Available for: Windows | Linux | Mac | Other systems

CDBurnerXP Pro - easy to use, looks nice, works (it can also burns DVD's). A great freeware burner.
Available for: Windows | Linux | Mac | Other systems

Office software

Suites:

602Pro PC SUITE - Good software (Czech made). Approximately 12Mb (pretty small, isn't it?). However, compatibility with Microsoft Office is rather poor.
Available for: Windows | Linux | Mac | Other systems

OpenOffice.org - One of the best office suites at all (comes from StarOffice by Sun Microsystems, one of the biggest Microsoft "enemies", OpenOffice is an open-source version of StarOffice, i.e. it is for free with source codes), it has around 41Mb and is available in many languages. Very good compatibility with Microsoft Office.
Available for: Windows | Linux | Mac | Other systems

EasyOffice Freeware - a nice and useful office suite + functions like editing and printing into PDF, 33 - 47 Mb, poor compatibility with Microsoft Office programs.
Available for: Windows | Linux | Mac | Other systems

Other office tools:

Usually all of those mentioned here offer standard functions, while the bonus stuff is also interesting.

Abiword - nice 'n' speedy. Doesn't have as many features as e. g. the word processor in OpenOffice yet remains higly usable for those not-so-demanding. Gnumeric is a spreadsheet program like OpenOffice's Calc or Microsoft's Excel but, like Abiword, is really fast and lightweight (and has excellent basic Excel file compatibility).
Available for: Windows | Linux | Mac | Other systems

Atlantis Nova - Here is interesting especially the possibility to save to supercompact rtf (it's still a Rich Text File, though), what can save some priceless disk space. With many functions, though lacking some other ones, this is a very good software.
Available for: Windows | Linux | Mac | Other systems

PDF tools:

Foxit PDF Reader - a speedy PDF viewer.
Available for: Windows | Linux | Mac | Other systems

Sumatra PDF - perhaps even faster than the Foxit PDF Reader, has most of what you might need for viewing simple PDFs. It also lacks some handy GUI features, but it makes up for with its speed.
Available for: Windows | Linux | Mac | Other systems

Adobe Reader - the big one, you surely know it if you use Windows. It's slow, but it fully supports the PDF file format with all it has.
Available for: Windows | Linux | Mac | Other systems

PDFCreator - a virtual PDF printer, it's pretty good one too.
Available for: Windows | Linux | Mac | Other systems

CutePDF Writer - another virtual PDF printer, I haven't used this one, but refences for it are generally good.
Available for: Windows | Linux | Mac | Other systems

doPDF - a virtual PDF printer, it features good output and printer options are nice and easy to orientate in.
Available for: Windows | Linux | Mac | Other systems

www editors

A WYSIWYG website editor: Namu6 - "Namu6 is a fast and easy way to create, maintain, and publish a website." Seems to be true in this case.
Available for: Windows | Linux | Mac | Other systems

Another one: Nvu - nice if you are used to any word processor.
Available for: Windows | Linux | Mac | Other systems

Simple CSS - a css authoring tool, pretty neat for a point and click program. Could be handy for initial css setups.
Available for: Windows | Linux | Mac | Other systems

CSE HTML Validator Lite - text editor with code checking ability. Otherwise pretty standard abilities but without page preview (internal/external). Pretty handy, although it loads slowly.
Available for: Windows | Linux | Mac | Other systems

HTML-Kit - one of the best freeware (X)HTML editors. Complex program with most things you could need creating simpler web pages. Loads very slowly.
Available for: Windows | Linux | Mac | Other systems

PSPad - for UTF-8 work, this beats most editors out there (and it has even more useful features than Crimson Editor).
Available for: Windows | Linux | Mac | Other systems

Crimson Editor - one of the best text editors you can get for free.
Available for: Windows | Linux | Mac | Other systems

Arachnophilia - this one's prety good as well.
Available for: Windows | Linux | Mac | Other systems

Programmer's Notepad - far more than just a Windows Notepad replacement. Although it's a fast one, it includes lots of features that can make you switch from Notepad, like syntax highlight, ....
Available for: Windows | Linux | Mac | Other systems

Other utilities

On the address www.freshdevices.com are three intesting programs: download manager (Fresh Download), a Windows tweaking tool (Fresh UI) and a benchmarking tool (Fresh Diagnose). All three are freeware! (and they aren't bad either)
Available for: Windows | Linux | Mac | Other systems

On the address BOINC - Berkeley Open Infrastructure for Network Computing: framework for projects such as SETI@home etc.
Available for: Windows | Linux | Mac | Other systems