You can install many commonly used Perl modules through the package management system. Over a thousand I think. Here's a list:

apt-cache search perl|grep ^lib

The benefit of installing via the package manager is you get updates. In case you're not familiar with APT (advanced packaging tool), there's a howto in the documentation.

CPAN has a much wider breadth though, so if a Perl module hasn't been packaged you can always use that.