Like superted mentioned - Spotify is one example. There's plenty more. A friend of mine is building LikeBright.com - it's a unique concept for a dating app that

Like superted mentioned - Spotify is one example. There's plenty more. A friend of mine is building LikeBright.com - it's a unique concept for a dating app that exists as a layer on top of the Facebook. FB auth is obviously a huge part of Facebook's extension beyond their walled garden, but there's plenty more examples. The fan-page widgets for social proof, Facebook Comments for publishers, and like-buttons are all areas of integration that solidify Facebook's lead. It's not just a site, and it's growing into being more than just a platform. Already, Facebook's certainly beyond anything any historical precedents have set before.