A First Look at Objective-C
   Article by Noah Roberts.
   http://www.gmonline.demon.co.uk/cscene/CS7/CS7-05.html

Categorically Speaking
   Article from Stepwise on the merits of Objective-C categories, with examples.
   http://www.stepwise.com/Articles/Technical/CategoricallySpeaking.html

Cetus Links - Objective-C
   Links on Objects, Components and Objective-C. Provides links on tutorial, newsletter, books, software and libraries.
   http://www.cetus-links.org/oo_objective_c.html

Cocoa: The Objective-C Programming Language
   A detailed introduction to object-oriented programming in the context of the Objective-C programming language.
   http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC/

Objective-C
   At the Portland Pattern Repository Wiki.
   http://c2.com/cgi/wiki?ObjectiveCee

Objective-C Beginner's Guide
   Tutorial in text and code samples. English, Chinese.
   http://www.otierney.net/objective-c.html

Objective-C Resources
   Directory Objective-C resources.
   http://www.foldr.org/~michaelw/objective-c/

Objective-C is Fun
   A simple introduction to Objective-C, from the GNUstep project. By Adam Fedor.
   http://www.gnustep.org/resources/ObjCFun.html

Optimizing Objective-C Code
   Articles and samples to help you get maximum performance from your Objective-C code.
   http://www.mulle-kybernetik.com/artikel/Optimization/opti.html

Programming in Objective-C
   Some introductory notes and examples of Objective-C.
   http://www.cs.indiana.edu/classes/c304/oop-intro.html

Programming: Objective-C
   Includes tutorials, reference material and downloads.
   http://www.toodarkpark.org/computers/programs/objc.html

comp.lang.objective-c FAQ
   Frequently asked questions about Objective-C.
   ftp://rtfm.mit.edu/pub/faqs/computer-lang/Objective-C/faq