Leonardo
   An integrated environment for the development, reversible execution, logic-based animation and visual debugging of C programs. Snapshots, animations, online manual, download and related links too.
   http://www.dis.uniroma1.it/~demetres/Leonardo/

Macintosh C Carbon
   a hobbyist's guide to programming on the Macintosh
   http://www.mactech.com/macintosh-c/