From Programmable Web:

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.

This Foursquare API-based web app (the iPhone app, which is literally a giant compass pointing towards said ladies, is coming soon)

It apparently started as a joke… but has become really popular.  What a brilliantly funny way to reuse public location data.