This article (with source code and project files) shows how to make a simple XML-RPC call with the new-in-Jaguar WebServicesCore framework.
This HowTo shows how to use an NSScanner to do simple syntax coloring.
This open source (BSD license) class parses RSS files using CoreFoundation routines.
This open source (BSD license) Cocoa class parses OPML files.
Some cool Cocoa websites...
Searchable archives for the Cocoa and MacOSX developers mailing lists.
Lots of articles and HowTos organized by topic.
Cocoa Dev Central
Lots more articles and HowTos.
All kinds of tutorials and docs on Cocoa.
Articles and news for Cocoa developers.
The Cocoa Files
Articles by Andrew Stone of Stone Design.