I am learning Cocoa programming these days, and am actually picking it up very quickly. As I have mentioned in the past, it reminds me a lot of SmallTalk programming. Below are some sites/resources that I am finding really helpful. I’ll update the list from time to time.

COCOABUILDER.COM – A perfect interface to both Cocoa mailinglists
MACDEVCENTER – O’Reilly’s Mac Developer page
COCOADEV.COM – WikiWikiWeb site for the developer community
COCOADEVCENTRAL – A site with great tutorials
COCOA FAQ – Frequently Asked Questions
STEPWISE – A classic site on Objective-C
HYPERJEFF – Cocoa Literature
REFERENCE LIBRARY – The official Cocoa Reference Library
MACRESEARCH.ORG – Macs for Scientists