NetRadiant is a fork of the GtkRadiant 1.5 editor, aiming to stabilize and bugfix the included q3map2 map compiler.
LiquidMac uses a particle system to imitate liquid and responds to laptop orientation.
Wineskin Winery creates Mac OS X ports/wrappers for Windows programs/games, with an easy-to-use GUI, integrated Wine, X11 and an installer.
