Unix Network Programming (by Stevens) Amazon BN
In-depth documentation on network programming, including Berkeley sockets. A must-have if you're doing any serious network programming with sockets.
Code Samples for Chapter 13 (Networking)
Includes addresses.m, chatterclient.m, chatterserver.m, simpleclient.m, simpleserver.m
Beej's Guide to Network Programming
An easy introduction to Berkeley sockets.Writing Networked Simulations (can you say "games"?)
Matt Slot (of Ambrosia Software) has written a series of essays about issues involved in writing a networked game.Networking Frameworks Comparison
Stepwise has a survey of various Objective-C wrappers for BSD sockets.