The Facebook SDK for PHP enables developers to access the Facebook Graph API and use the Facebook Login from within PHP applications. Examples are provided that show how to use the SDK to retrieve a user's profile, post a link to a user's feed, and upload a photo to a user's profile.
Defensio, the anti-spam service, offers an API that can be integrated into blogs and web sites to fight spam comments and other unwanted spam (details at our Defension API profile). The service appears to be run by a small team, and is similar in purpose to Akismet, the much larger spam filtering service from Automattic (which powers WordPress.com), who also offer an anti-spam API.
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.