Every day, there are three reasons I hug Perl when I use it, and curse other language when I use them. In no certain order:
#1. CPAN. It just can't be beat by another other language.
#2. Test::*, TAP and Devel::Cover. Perl has very strong testing/coverage facilities. I love using it. I love writing tests, and I love enjoying a good refactor without all hell breaking loose.
#3. MI, ISA, InsideOut, Mixins, C3 and Moose. I love that Perl just gets the hell out of my way, and doesn't insist that I subscribe to a particular form of single/multiple/implementation/interface inheritance. I can make it do what I need it to do.