I just got my copy of Ajax Hacks (I’ve contributed couple of chapters). It happens to be one of their bestsellers, btw.
I was supposed to get the book quite sometime back, but since I didn’t, I was asked to choose any O'Reilly book of my choice. Now that was not an easy thing to do: I couldn’t think of anything that I wanted bad. (I would have asked for any book on Haskell or OCaml, but they don’t seem to have any books on functional programming languages.) I ended up asking for AppleScript: The Definitive Guide. What book would you have chosen?