Every day Foursquare users create millions of check-ins using the location-sharing platform. Those may be only a small fraction of the traffic seen by its API, which we've estimated receives at least 5 billion requests per month. The company continues to expand the local data made available via its API, so developers of all sorts are finding it a rich resource for building their apps.
While many are excited about live traffic data on firm ground, others have turned their attention to the other 3/4 of the earth. According to The Map Room, many ships are required to carry transponders to broadcast their location. The result is a lot of public marine data and the perfect situation for a classic map mashup.