Poe - For multiple work projects and because it looks cool.
Class::DBI - Having used SQL a fair bit, trying not to think "Well with SQL I could do this by
eXtreme Programming - I've been asked at work what development methodolgy we use. Adhoc doesn't seem to be the answer they wanted. As XP appears closest to the method we're using I answered that we're moving in that direction. Now to learn about it, and teach the others.
Template Toolkit - Our application is currently developed with a PHP web front end. We've found that maintaining the PHP code in a multi-developer environment difficult. As such a migration to an MVC design is now in progress and TT will be our templating system. I'm reading the Badger book now, it's quite good.
mod_perl - Exact same reason as TT.
PAR - We have a number of servers that are missing Perl modules that our application relies on. If PAR works the way I think it does, it'll solve this issue without impacting our customers.
Above all of this is increasing my Perl skills. I've learned a lot in the last 6 months, but I know there is much more for me to learn and improve on.
There are many others, like I said this is the small list.