Many years ago, there was a Perl quiz of the week (actually it was two quizzes: regular and expert). The regular quiz was aimed at coders who had finished reading Learning Perl.

There are archives of the regular quiz problems & solutions and the same again for the expert problems & solutions

There was another mailing list to discuss each of the problems and its archive can be found here.

I hesitate to add this but Ruby also had a (much longer running) quiz of the week. You can find their list of problems (some are the same as the Perl questions) here.