I would be interested in usage statistics of modules - though I can't say for sure why it would be useful other than for spurious claims that popular equals good.

A fairly quick way to get usage stats on more than just the modules that pop into everyone's head (classics like the DBI) would be if monks uploaded their perllocal.pod or autobundle to some website.

(I personally would disable any 'call-home' scheme to gather such data.)

You could even try to find clusters of modules commonly used together, in organically grown configurations ('webby', 'databasey', etc.)