I've just finished reading Robert Anton Wilson's Chaos and Beyond: The Best of Trajectories, a collection that's unique among his work.
For one thing, it's one of the few RAW books that has gone out of print -- I had to order it from a secondhand bookshop on the Internet. It also has lots of material from other writers, including Timothy Leary and Arlen Wilson, Robert Anton Wilson's wife.
It doesn't seem quite as essential as some of Wilson's other books, but I enjoyed it and thought it had some really good material. Much of the best stuff is in the back of the book, including Wilson's review of Hakim Bey's Temporary Autonomous Zone and a book review that discussed Philip K. Dick, which I would reprint here if I could figure out how to obtain permission.