Mac OS 8 and 9 Developer Documentation
- Gateway to Apple's documentation for programming Mac OS 8 and 9, including Carbon development.
- http://developer.apple.com/macos/

MacOS Web Directory
- A directory of Mac programming related sites, including development kits, format specs, toolkits, open source, tutorials, and webzines.
- http://www.strout.net/macweb.cgi?dir=/Programming

GNUstep Project
- A project devoted to providing an object oriented application framework to developers.
- http://www.gnustep.org/

Sound & Vision, Inc.
- Develop software for Macintosh platform. On this site users can find information about FineReader 5 Pro, development and layout software.
- http://www.softformac.com/

Macdev at MIT
- Various resources for Macintosh development from the folks over at MIT.
- http://web.mit.edu/macdev/

MacHack
- "The Annual Conference for Leading Edge Developers"; a multi-day round-the-clock ritual involving gallons of soda, heinous hacks, and lots of camaraderie. Not to be missed!
- http://www.machack.com/

iDevGames
- Macintosh game development website featuring news, tutorials, game assets, forums and articles.
- http://www.idevgames.com/