If your box at home is not already running Linux, I would suggest starting there - you will learn a great deal about shell commands, unix commands, C, and perhaps even venture into awk, all of which will reinforce your perl skills as all of them have parts that will seem very perl-ish. (Mostly because those parts were taken by perl!) Then try and compile your own kernel and try out some basic C programs. Unfortunately, modifying perl or the Linux kernel are not really beginner tasks. Compiling can be done, and even *some* source code tweaking is possible, but it might be easier to start with something smaller. Seek out a local Linux Users Group, and learn from them. Try implementing some of your perl scripts in other languages such as C, awk, csh. Play around with things (e.g. X, Apache, Mozilla, sendmail, lynx, the kernel) until you find something that really grabs your interest. Al of the previous are open source, which means you can dive right in to the source code (C, naturally) and get your hands dirty. It's hard to do this with something that doesn't really interest you, so play around with a lot of things until you find something that does. While none of it is *directly* related to perl, I think it's definitely a step in the right direction.

I'd also recommend reading all the perldocs if you have not done so already. Perlhack, perlguts, perltoot, perl5005delta, perlmod, perlfaq\d?, and perlboot come to mind of the top of my head.

Another good way is to try and decipher some obfuscated code, or even just non-obfuscated code, and make sure you understand how it works. Plenty of examples of both on this site. Try writing your own version of something fun, like my Animals program, but maybe without the references, or try writing a C version, or just figure out a wat ot write it that is easier-to-read/obfuscated/quicker/smaller/etc.