Thanks for the good question; I've appreciated the answers as well. I have enjoyed doing much of what was mentioned above, such as going through the code/writing my own packages, and trying new things. In addition, here are my takes/recommendations on a few books:

• Modern Perl (by chromatic) was the first one I picked up, but I found the structure of it a bit difficult for a newbie. I switched to Learning Perl and Beginning Perl to better effect. I especially recommend Beginning Perl.
• Intermediate Perl and Programming Perl are next on my list. Programming Perl is supposed to be one of the classics, and bears Larry's name itself.
• I haven't heard it mentioned much, but I am ABSOLUTELY impressed with "Mastering Algorithms with Perl," which is the equivalent of a data structures text book executed in Perl and has loads of hints that help to understand the guts of Perl (not to mention countless insights and code samples about referencing and doing all kinds of clandestine things with hashes, arrays, and references).

Finally, I wish I had sooner learned to start every program with:

use strict;
use warnings;
use diagnostics;
[download]

I'm sure you've seen the first two around everywhere; the last one supplements them with verbose warnings that give you full suggestions on what the problem might be, often including working suggestion examples. Not necessary for Perl pros, but if you are like me and can get lost in obscure meanings of the brackets, parenthesis, and commas, diagnostics is a life saver.