From time to time I find myself wondering what module a given Drupal site uses to perform some nifty action or another. A while back I found a tool that helps with that spy work for WordPress called simply What WordPress Theme is that? And then I finally found Drupal X-Ray, which does the same thing for Drupal sites.
Oh, and if you're not sure which CMS (Content Management System) you're looking at, try http://whatcms.org/
Happy snooping!