The two most useful books I’ve seen for JavaScript webmasters are Webmaster in a Nutshell, which is simply a useful reference for all sorts of webmaster information, and JavaScript: The Definitive Guide (http://www.hoboes.com/Books/javascript.shtml), by David Flanagan. You’ll find links to both of these on my Recommended Software page at http://www.hoboes.com/NetLife/NSpace/software.shtml.
Thanks go to Joy Brunetti (http://www.sandiego.edu/~brunetti/) for testing out the sample scripts and being the first guinea pig!
“The best book on programming for the layman is Alice in Wonderland; but that’s because it’s the best book on anything for the layman.”