Techstra for Aaron's Cocoa Programming book
Check this out. Techstra makes it possible to supplement the provided material with author and reader provided errata, samples, comments, and links to related internet resources.
http://www.techstra.net/books/bignerd/
This makes a book a community. Right on.
(When you go there, choose the first edition and look for page 56. That's a good sample...)
Written on January 15, 2002