Common LISP: The Language, 2nd ed. A good book if you want to have the whole LISP language at your fingertips. Each function's discussion is reasonably detailed, but you won't find many examples of how to use the functions. Also available online.
RCX Command Center - An editor+compiler environment (requires NQC) for programming RCXs.
Gordon's BRICK PROGRAMMER - An alternative "tree-based" editor+compiler environment for programming RCXs.
Real-Time Controller - A package by Clint Rutkas for using your PC as a remote control for a MindStorms robot.
AI Resources
AI Resource List - A *HUGE* collection of AI links, maintained by Stuart Russell as a complement to his book, "Artificial
Intelligence: A Modern Approach."