In my mind, Foursquare history remains one of the most interesting features of the service. It knows basically everywhere I’ve been since 2009 (actually, 2008 thanks to some imported Dodgeball data). To some, that’s creepy — to me, that’s awesome.
Recommendations are the obvious use case for past data. But as we’re seeing with services ranging from Facebook Timeline to Timehop, don’t underestimate the power of nostalgia.