An impressive package (even content filtering in Squid is more cumbersome), very useful and flexible to extensions.
A very interesting module for doing backup. Require a bunch of perl modules but seems very promising in the future. The system is keeping metadata and you are able to restore specific revision of files. Nice to have when you want to avoid a full blown backup system in a DMZ.
Don't reinvent the wheel of regexes. A must to have in his own Perl toolbox or module.
A very nice and nifty perl module. The documentation is very good and explains everything needed when using it. Locking is supported and the API to access the DBM is covering different approaches.
An excellent module for creating "apache-like" configuration. Every program using Perl should use this for his configuration file.