feature request: dynamic rules for ad widget

The default rules are interesting, but don't provide enough range of options. What if I want to show different ads to new users than old users? Ads for mobile devices? A different content block to administrators? Ads for users only coming from a specific source? Geotargeting?

It would only take a couple of filters to add custom rules to this plugin so that these could each be added by the site owner pretty easily. Is this something you'd consider including?