I'm just starting with perl, but in the past few months, I've found the following sites invaluable: the're chinese mirrors of O'Reilly's Safari bookshelf.

At URL removed you'll find:
Perl in a Nutshell, 2nd Edition
Programming Perl, 3rd Edition
Learning Perl, 3rd Edition
Perl Cookbook
Perl and XML
Perl and LWP
Mastering Perl/Tk


Beginning Perl for Bioinformatics can be found at URL removed.

And the The Linux Web Server CD Bookshelf (which includes "Programming the Perl DBI" and "CGI Programming with Perl."), is at URL removed.

It's probably completly illegal, and O'Reilly is possibly quite unhappy with them, but they were a godsend for me

Update: Following some discussion on the chatterbox, let me add this disclaimer: I don't have anything against O'Reilly. Some of my most cherised Perl/bioinformatics books in my library are from them. And I'll be first in the row in November when their R for bioinformatics comes out in November. But when searching for answers on perl related questions, those sites where invariable among the top Google hits.

Update 2:To honor jZed's request I've removed the URL's. And sorry for the emotions this stirred up. I wasn't aware that what I was doing, was negativly regarded upon in the community.