I'm currenly interning with a company and spending 95% of my time coding Perl - it's a great way to gain experience with a new language, as well as a pretty good way to meet people.

Having said that, though, from experience it seems that such positions are very hard to come by at the minute, either paid or otherwise. While I'm sure companies would love to have "volunteer" staff on their books (read: cheap labour), there are almost certainly legal issues they would have to address, especially as employees have rights as employees, whether they get paid or not.

Another thing to think about is how you'd finance yourself if you were doing voluntary work. You say yourself that you've been forced to accept several positions - I assume you'd need to keep a paid job as well? This could cause problems with your current employer: many contracts seem to have a clause stating that you can't carry out other "professional work that may interfere with your duties" while in employment.

I think that I'd tend to agree with some of the other comments and look for projects writing Perl that are based either online or completely outside the scope of employment. That way you have the benefit/enjoyment of coding Perl, some social events (I'd hope ..) and maybe avoid problems with your employer further down the line.

Just my thoughts ..
--Foxcub