I also described this need a while back. I made a pragmatic module called use logged; and I thought I posted it here but can't find a link.

It's very similar to my module called use deprecated; and you might look at that one for some ideas. Just log a caller the first time a script loads your module, and you'll get a good sense of the user community on your network.

Of course, the best logging approach will vary on your network setup. This was raised as the worry of spyware here last week, but within a corporate network or filesystem, I think it's fair game for the librarian to track usage occasionally.