You could always try SourceForge and see if there are any Perl projects that are "recruiting". By using CVS and supplying patches, or other contributions, you can code large or small, as it suits your style.

Additionally, other programs are always in need of a little utility or config tool which would be really handy but nobody has bothered to write because they are busy with other things. Even a one-liner, if useful, could be adopted into the distribution. You never know.