You've definitely hit on the truth -- you just can't learn how to write decent code (or do much of anything else, for that matter) by reading books, man pages, or websites: you have to do. I'm not sure that exercises are the way to go, though. I learn a lot better if I have some real task to do, something more motivating than a contrived exercise.

Instead of (or as well as: since people learn in different ways, the more resources PM has the better) exercises, how about a list of common, useful tasks that perl's really good for? We could provide links to useful information (or at least pointers to the right man pages), some examples, and so on: the idea wouldn't be to get people to solve the problems presented, but to spark the "hey, wouldn't it be cool if..." train of thought, and give enough help that they wouldn't run into brick walls.

Some stuff that I can think of, off the top of my head:

• log parsing
• web page automation
• document translation

This would also be a great way to introduce people to CPAN, and especially to idiomatic ways of doing things in Perl. (My most common learning experience, especially with Perl, is to do something the first way that comes to mind, then a few weeks later find the right idiom for the job -- and suddenly my code is half as big, twice as effective, and four times as readable. And short of reading good code, it's difficult to find idioms easily.)

--
:wq