A CPAN search for "database pool" yielded ResourcePool. I haven't tried it yet, and even though the module seems to be written with mod_perl in mind, the docs do mention that it is "useful in stand alone perl applications." Looks like it is worth a test run. You might want to start your RTFM'ing at ResourcePool::BigPicture.

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)