Realpolitik is a cross-platform (Mac/Win32) viewer and adjudicator for the game Diplomacy, with a point-and-click interface, game history, and text and bitmap reports for GMs. It has over a dozen rule and map variants, and you can easily create your own
BrickDraw3D is a MacOS program for building with virtual Lego bricks. It is based on the LDraw parts library and is useful for viewing and editing models in the DAT format. See http://olson.pair.com/brickdraw3d/ for examples.
FMSync is Macintosh software that provides sychronization between FileMaker Pro and the Palm application JFile.
This is a collection of Perl modules for accessing the Mac OS (Carbon) API. It was designed for use on Mac OS, but is being ported for use on Mac OS X as well.