CPAN is the magic bullet that all other languages envy.
It's a vast repository of modules that people have contributed.
It stands for Comprehensive Perl Archive Network.
http://search.cpan.org is the standard front-end to search the CPAN. It also includes links to most of the rest of these sites.
There's a different interface to CPAN at https://metacpan.org. metacpan.org has more features and links for exploring the CPAN and distributions.
http://cpanratings.perl.org lets you rate and comment on modules and see what others thought of them, before you try.
Submit your bug to RT at http://rt.cpan.org.
http://annocpan.org lets you annotate the documentation for a module, with the hope that the author will incorporate the changes in the future.
http://backpan.perl.org/ has every module ever on CPAN, even if it's old and out of date.