It's really great when a company like iD Software release their game engines under a Free license. It means all the hard work by modders (the vast majority of community game development goes into modding commercial games) can be made available to everybody and not just owners of the game. It also means they can improve the engine to suit their games. So, without further ado, here's a few really cool total conversions of Quake 3...
Western Quake 3 is a wild west TC. Accurately simulated classic weapons, new music, obviously models and maps, and various gameplay tweaks mean it should be quite an interesting experience. Still in beta but a new release is imminent.
Urban Terror made a release on April 1st. It's a Counter-Strike-like game. 'Nuff said.
Tremulous, one of the original FPS RTS combo games, recently celebrated the 1 year anniverisary of their 1.1 release - the first standalone version of the game and the one that really got people talking. Since then there has never been a moment when somebody was not playing the game. They posted an interesting graph depicting play activity. A new release (1.2) is imminent.
Bid For Power is a rather cool looking Dragonball Z TC for Quake 3. Unfortunately they only have a Windows version at the moment.
Spiderman: Dynamic Forces looks cool. Sadly they got sent a cease & desist order by Marvel. Fans making games is wrong, apparently?
World of Padman is a Toy Story-like game, whose inaugral release was on April 1st as well. It's no joke either! In fact, it's a rather fun game. :-)
If only other game engines were released as Free Software, then mods like Air Buccaneers (Unreal Tournament 2004 TC) could become standalone free/Free games too.
Are there any other interesting Q3 TCs not mentioned here? I did a little digging (I'm a bit busy today) but came up with not-much.
Absolut feat. V-Tunes - Boxrocker