The books on NLP I've seen all seem to be poorly written. Some of them are basically just transcripts of live NLP seminars, and a lot of the books seem to be geared towards therapists who are planning to use NLP with their clients -- doesn't seem to be too many general-purpose books for the layperson.
I wrote a short, general introduction to NLP as an e-book a few months ago -- if anyone here wants to download it and give me some feedback, feel free:
http://speakeasy.org/~strong1/nlp.pdf
(.pdf file)
-Ken S.