Considering the nature of the site, the nature of its nurture, and its prime subject matter, I'd have thought the Perl license most appropriate. For example (taken from XML::Twig):

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

A few pertinent links are:

• Licensing Revisited ... again and again.
• Licensing of Perl Modules (note this in particular)
• ~OT Licens(?:es)|(?:ing)
• GPL and LGPL linkage to Perl
• Using GPL'd Perl Modules in Commercial Software
• To Open Or Not To Open
• Licensing your software
• What would you do if you were Larry Wall?
• Licensing and Rape-Proofing your ideals.
• my new software license.

A few directly pertinent, a few cautionary tales, and at least one that is just a bit wierd.