I have worked on various pieces of the perl distribution over the years, mostly related to issues of Configuring, building, and installing perl. In 2002, the kind folks at ActiveState gave me a nice ActiveAward award for my work.
Check out the Perl.org and Perl.com home pages for Perl sources, documentation, and other resources. Developers should also visit http://dev.perl.org/ for yet more resources.
One somewhat larger project is an on-line homework system, originally derived from Larry Martin's WWWAssign project. A distant relative of that project is the commercial WebAssign homework system.
A second project is temperature control for my research in dendritic crystal growth. My temperature control system is written in perl (with a few custom XS modules). Originally, I developed it in perl as a prototype, but it proved sufficiently robust and flexible that I still use it today.
Mostly, though, perl is simply the indispensible glue that holds everything else together and allows me to do my work.