Some OS X links from today's travels:

Flurry's a cool screensaver for OS X that includes the source.
Epicware also has a hefty collection of screensavers along with source.
Jerry Kindall links to OS X Unix Tricks and Tips, including a nice tweak for Terminal.
Be sure to visit Hyperjeff and his great collection of links to Cocoa apps w/source. He also has a growing collection of Music and Audio apps.
Camelbones? It's a high-level Objective-C framework that wraps around the Perl embedding API.