I didn't see it mentioned -- so here is my choice.
By far the book I use most is O'Reilly's "Programming Perl". "Learning Perl" with lots of bookmarks and dirty pages is second.
On a related note, I'm looking for a book on graphics. A few years ago, I bought "Mastering Perl/Tk" and got a few useful things working. But then Tkx came out and I'm lost again. I have studied the much-touted TkDocs tutorial, but it leaves too many holes for me. ActiveState and others list all of the functions and their options, but I can't bridge the gaps. I saw and bought another book recently, O'Reilly's "Perl Graphics Programming", but was disappointed that it doesn't even mention either Tk or Tkx.
What else is out there that am I missing?