Arciem Engineering
   Provides custom software development and design for Mac OS X.
   http://www.arciem.com/

Epicware
   Providing free and open source software, tips and tricks, games, and screen savers for Mac OS X Server and Mac OS X.
   http://www.epicware.com/

OpenBase International
   Database solutions for Mac OS X.
   http://www.openbase.com/

Stone Design
   Provides productivity applications and software engineering for Mac OS X and related systems.
   http://www.stone.com/

The Omni Group
   Creators of OSX applications OmniGraffle, OmniOutliner, OmniDisksweeper and OmniWeb.
   http://www.omnigroup.com/