ghenry,
I am a bit of a bibliophile and a firm believer in having reference material "just in case". With that said, I haven't read a single one of these books all the way through.

• Higher Order Perl
• Programming Perl
• Advanced Perl Programming
• Perl For System Administration
• CGI Programming With Perl
• Mastering Algorithms With Perl
• Extending And Embedding Perl
• Learning Perl
• Learning Perl Objects, References & Modules
• Perl Cookbook
• Object Oriented Perl
• Network Programming With Perl
• Effective Perl Programming
• Perl 6 And Parrot Essentials

Of course, this doesn't include all the peripherally related books on regular expressions, SQL, etc.