In agreement with/addition to the already great suggestions, I would recommend ...
Programming Perl This is an indespensible reference
Perl Cookbook The explanations say a lot about perl programming and philosophy
Programming Pearls (Jon Bently) This book isn'nt Perl specific but it has a lot of good, solid practical discussions on programming practice and methods. The practice problems are interesting and relevent. Try to get both the 1st and 2nd editions as they have somewhat different content, both are invaluable.
Update: I stand (sit actually) corrected :o)
PJ
unspoken but ever present -- use strict; use warnings; use diagnostics; (if needed)