I keep Perl In A Nutshell on my desk, left-side front. In addition to the Camel, Testing, and Damian on OO I also keep Perl Cookbook in the book shelf over the monitor.

Actually I have two copies of all five books -- the current copy at work and the older copy a home. You never know when you will need to look something up.... (Note: I am at home today, recovering from a vacation. The ISBN numbers are for the versions I have at hand here, I know that both the Nutshell an Cookbook have newer editions.)