I divide my world to Within-Arms-Reach and Everything-Else, and different sets of books make it into those two worlds. The close world is stuff I need to look up, so there aren't many Perl books there. The far world is the stuff I should already know.

Within-Arms-Reach

• Mastering Perl/Tk (it's a Stonehenge textbook and I'm reworking the class)
• Perl Template Toolkit (often used because I'm a Template dabbler)
• Version Control with Subversion
• Learning Perl Objects, References, and Modules (three copies: it's a Stonehenge textbook and I'm heading up the rewrite)
• Cascading Style Sheets (there's funny story there, and the same story from another perspective).
• CSS Cookbook
• Programming Python
• Programming Ruby
• PostgreSQL Developer's Handbook
• Open Source Development with CVS
• PDF Hacks
• Managing Projects with make
• HTTP: The Definitive Guide (although I mostly just reference the RFC)

Everything Else

Nearby are several piles of books that only seem to be getting taller. The technical ones include:

• Pro Perl, the latest from Apress
• XML Hacks
• The Art of Assembly Language
• Beginning Perl (reviewed in TPR 1.2)
• CSS Cookbook (huh, second copy)
• Amazon Hacks
• Google Hacks
• High Performance mysql (although I've been using postgresql mostly)

Much farther away is almost every Perl book ever written, and only almost because I managed to sell a couple of the ancient ones on Amazon. I mostly keep those around so I can answer questions a Perl newbie might ask about page X in Foo.