I guess since i'm here i'll make this thead 
also this technically isn't a mod.
OpenArena project just needs a texture artist. A modeler and skinner are also wanted but they're a bit less priority. Mappers are also welcome, though at the moment i'm just converting some of these. Coder is irrelevant because it's just vanilla gameplay (there are q3 mods that can run on OA anyway). Anyone can contribute to this project, as long as the submissions comply with the GNU GPL license you are set. Due to this license you may not want to submit your portfolio showcase work.
It's basically the "free software" version of Quake III Arena, which is recreated from scratch, not using any q3 assets (just the ioq3 engine, but that's not an asset itself) and also all GPL licensed. Poor man's q3a basically, but free software. Q3A is not required, just OpenGL and a suitable operating system (Windows, Linux, mac maybe)
A long description isn't really needed since the game is quite simple anyway. If you've played Q3A, then you know what this is.
The site's here, with a slightly out-of-date stable release, and a SVN repository is available