Learning Perl (3rd Edition)
Perl is the most common language for CGI programming, and it can be thought of as the "Swiss army knife of the Internet." It's also an extremely powerful scripting language for anything at all to do with batch processing of text. It can be a "write-only" language so it's harder to learn by studying other folks' code than many other languages. This book brings you up to speed quickly and thoroughly.
I'm still using the 2nd edition, so this item is on My Wishlist