You can't forget about these. I find that these topics come up most often here on Perl Monks.

Programming the Perl DBI Database programming with Perl By Alligator Descartes & Tim Bunce
Mastering Perl/Tk Graphical User Interfaces in Perl By Steve Lidie & Nancy Walsh
CGI Programming with Perl, 2nd Edition By Scott Guelich, Shishir Gundavaram & Gunther Birznieks

This doesn't mean that O'reilly is necessarily the best books, but they are very good and they look good on your book shelf.

I personally have the following:

Programming the Perl DBI Database programming with Perl By Alligator Descartes & Tim Bunce
Mastering Perl/Tk Graphical User Interfaces in Perl By Steve Lidie & Nancy Walsh
CGI Programming with Perl, 2nd Edition By Scott Guelich, Shishir Gundavaram & Gunther Birznieks
Perl for System Administration Managing multi-platform Environments with Perl By David N. Blank-Edelman
Programming Perl, 3rd Edition By Larry Wall, Tom Christiansen & Jon Orwant
Advanced Perl Programming By Sriram Srinivasan
As well as 2 black books on Perl.

I have this on my wish list:
Mastering Algorithms with Perl By Jon Orwant, Jarkko Hietaniemi & John Macdonald

Sparky