Take Dave Cantrell's CPAN Dependency checker for a spin. Give it a couple of big packages like Plagger, Catalyst, Jifty, Mail::SpamAssassin or POE and see what it thinks of them.

Look for the usual suspects (modules that come up repeatedly with lots of failure), and that deal with problem domains you're interested in.

Check out the corresponding CPAN RT queue and see if there are two hundred new bug reports filed. There's a fair chance that the author has gone AWOL. Download the package, fix the bugs, while trying to contact the author in parallel.

After three months is up, and you've fixed all the bugs, and the author hasn't acknowledged your polite queries as to whether they still wish to maintain the module, or want a co-maint, or whatever, you should then drop a line to module-authors@perl.org detailing your attempts to fix the module and track down the author.

Depending on a number of factors, you might just wind up as the proud maintainer of any number of crucial CPAN modules. And I would buy you a beer if we ever meet up at a YAPC.