I've not put many links up here yet.Sorry.

• Dillo: Nice little browser for Linux and Unix- very small and very fast and rather stable; I use it quite a lot. If you have a machine that this browser works on, I recommend you give it a try, as long as you don't mind that it lacks certain features. NB: It's been made clear that Dillo is a closed project, and if you want to either contribute or use patches for it, you should see the Dillo Patches mailing list. Questions regarding patched versions of Dillo should be directed to those responsible for them.
• Blender: A strange integrated 3d graphics system that is sort of part modeller, part renderer, part scene graph. I don't really know how exactly to describe it best. I do find it pretty confusing due to the unusual user interface, but there's plenty of people who swear by it. Personally, I think I'm more likely to swear at it.

  Still, some people have produced very impressive work with it, and it works on most (all?) operating systems.

• Wings 3D: A great free cross-platform 3D modeller, originally inspired by "Nendo". It's what's known as a "subdivision modeller", and works with structures known as "winged edges" (hence the name). It's pretty versatile, and is improving all the time.
• The GIMP: The Open Source / Free Software graphics manipulation program. Often described as a free version of Photoshop, except this unfortunately makes Photoshop users try it and scream "This is rubbish! I can't do anything!" - but a clue: just because it can do most of the same things as photoshop, doesn't mean it works the same as Photoshop. Still, I do find a good few things about it very annoying.
• Open Office: The Open Source / Free Software word-processing and general office-type software package thing. If you can't understand that, think in terms of Microsoft Office, but free, cross-platform, with somewhat different user interfaces, and without the attempts to lock you in with evil proprietary file formats.
• GNUnet: An anonymous peer-to-peer network framework, which currently has a censorship-resistant filesharing system implemented with it. If, for example, you use some other filesharing system, and frequently worry that some IP syndicate is going to sue you into oblivion (correctly or otherwise) for copyright infringement, you might well consider this sort of thing useful.

  OTOH, you might have content of your own that you want to legitimately share with the world, but bandwidth costs for a website would be huge if your content was very popular, or you think others might (perhaps for reasons other than simple malice) want to disrupt your attempts to share it. In which case, GNUnet could be useful here too (GNUnet smoothly securely allows content to spread across the network, improving accessibility and reducing strain on any individual machine). WARNING: So far, GNUnet only works for Unix; Versions for Mac and Windows are being worked on but aren't ready. (NB: I used to have some pages about GNUnet around here, but I'm taking them down because I've not been keeping them up-to-date, and they've got far too stale to be helpful)

• MPlayer: One of the best media players for Linux and other versions of Unix. Plays almost every sort of file, and is pretty damned fast. Not intended for use with Windows.
• Ogg Vorbis: The cost-free, patent-free, high-quality, compressed audio format. Huh? You're probably familiar with MP3, right? It's "internet music", which lets you freely convert your music into much smaller files that you can share with your friends or put on your web page. Well, not quite. Turns out MP3 is patented, and anybody making free MP3 software is breaking the law as they can't pay to do so. On top of that, there's much talk of Fraunhoffer (who hold the patent) demanding royalties from artists and others who distribute MP3s because of use of their file format! Sounds like fun?

  So along came a bunch of similarly clever programmers, who created the Ogg Vorbis audio compression format, wrote software to work with that format, and (IIRC) placed the format in the public domain, for the general good of the world. On top of that, they made sure that music compressed with Ogg Vorbis would actually sound better than MP3s of the same file size! Thanks to their generosity and open approach to software, it is supported on pretty much all operating systems and computer types, plus some home audio equipment. Why are you not using this yourself already? GO GET IT!

I'm still not sure if these should go under "Fun" or "Software", but whatever.

• Nethack: One of the first Roguelike games I ever played. Still excellent. If I make some sort of a Roguelike links page, I'll probably move this link there!
• Kobo Deluxe: Improved version of the excellent old-school 2d shoot-em-up "XKobo" (which might have been a clone of another game, but not to my knowledge), works on pretty much every system, and has (AFAICT) all the brilliance of the original plus things like sound and music ;)
• Globulation2: A free RTS (Real Time Strategy) game, still in development but quite playable already (currently 0.8.8 as I write this). The only thing that makes it incomplete IMO is the bugs (which are few but significant), and that it's a bit slow on old machines. Some people have said the graphics are bad, but they look excellent to me.