Bobs Bookmarks
nehe opengl tutorials
Neon Helium (NeHe) is a site that contains a large number of opengl tutorial with the source code available for lots of different languages and frameworks. Very good for learning opengl.
http://nehe.gamedev.net/Wormux
Wormux is a cross platform gpl came written in c++. It is basically a worms clone but looks pretty damn good and works well.
http://www.wormux.org/phpboost/news/news.phptags: c++ games opensource
Ubuntu games arena
Archived list of free and commercial games available on linux
http://gwos.org/doku.php/games:starttags: games opensource
Alfith
Website of a nice man who makes some simple free opensource games. Nice example of c++ using sdl.
http://members.gamedev.net/alfith/tags: c++ games opensource sdl
Free Game Arts
website that contains links to free game content such as sounds, images and textures.
http://freegamearts.tuxfamily.org/
0 A.D. -- Wildfire Games
Very very good looking opensource RTS, under development for years and probably still a couple of years out of completion. Recently open sourced the entire project and making better progress
http://wildfiregames.com/0ad/List of Physics Games » Fun-Motion
large list of tested and reviewed physics based games, free and non free, mostly non free/non open source.
http://www.fun-motion.com/list-of-physics-games/tags: games
PokerTH - Community Portal
PokerTH is a well coded cross platform poker client with network protocol. Written in qt4 with c++
http://www.pokerth.net/FreeCol - Home
Cross platform free open source game based on Colonization and similar to civilization.
http://www.freecol.org/tags: games