The XQuartz project is an open-source effort to create a version of the X.org X Window System that is compatible with Mac OS X. This project's updates are not from Apple, but are instead a way for users to stay up to date with progress made in the open source community.
Wineskin Winery creates Mac OS X ports/wrappers for Windows programs/games, with an easy-to-use GUI, integrated Wine, X11 and an installer.
LiquidMac uses a particle system to imitate liquid and responds to laptop orientation.
