Here's my 10 faves, in no particular order:
- HTML::Template - For keeping Perl tidy
- DBI - Because I shouldn't have to change my programs because I change databases
- XML::Simple - I don't know much about XML, but this has been a help to me
- Mail::SpamAssassin - Because I HATE SPAM!
- File::Slurp - It frequently helps me save a few lines of code here and there
- CGI::Carp - Still too many dumb mistakes
- CGI - When it has to be done quick and dirty, accept no subsitute.
- Archive::Zip - Makes delivering our applications and other stuff to our clients a breeze
- Imager - Tremendously easy to work with images and scanned documents
- LWP::UserAgent - Too many uses to list.
There's more I love and use, but these are the ones that have served me best, from my baby Perl days till now (only slightly better than baby Perl, I'd imagine :P)