A promotional collaboration between Zynga and Lady Gaga has given rise to GagaVille, a special neighboring farm in FarmVille. Players who visit GagaVille following its launch on May 17th will be able to listen to exclusive, un-released tracks from Gaga's upcoming album, Born this Way. Additionally, Gaga themed items will be available for many of Zynga's other titles and a daily "Words with Gaga" contest will be happening in Words with Friends.
How brilliant is that? Take one of the most popular musicians in the world, particularly amongst a demographic likely to use Facebook, and paint their name all over the biggest game on the service. This is going to draw in people who'd left, add new users and probably push quite a few records. Good marketing is sexier than good dancing, if you ask me.