iTerm2 is a terminal emulator for Mac OS X that does amazing things
Create native Mac applications from command line scripts
Google Toolbox for Mac
A conforming Objective-C WebSocket client library
SOGo Zero-Effort-Groupware
Radiation Spectrum Method : a modal BPM (Beam Propagation Method)
Mouse/keyboard record/replay and automation hotkeys/macros creation
Free flexible open source todo manager featuring hierarchical tasks
Porting of linux-gpib to Mac os x
Share one mouse, one keyboard and one clipboard between your computers
Cocos2d for iOS and OS X, built using Objective-C
Play your favorite Windows video games on Mac OS X
Music player - endlessly plays your music
Mac Port Editor and WSI Creator
...has moved to packetpeeper.org
A basic prime number sieve/tester.