Geo::Google::StaticMaps, which basically just transforms a map definition given as a bunch of nested hashes and arrays into a Static Maps API URL. It ought to support everything that the Static Maps API itself currently supports.
Yes, you read that title correctly. WhereTheLadies.At is, indeed, a thing that exists. Before you get start joking around, let's be honest. Checking in all the time on Foursquare has earned you nothing but Mayorships and a free slice of pizza every once in a while. Well, that's about to change.
The most popular API, in terms of mashup count, is far and away the Google Maps API, which accounts for 41% of all mashups. But when it comes to the most popular pair of APIs, Flickr and YouTube mashups are the most common. Not to be outdone, Google Maps joins Flickr in a near second place.