I gotta give credit where credit's due. I've long been a critic of Foursquare, insisting for years now that the app was useless. People would say, "No, I like that it shows my friends where I am." My reply to that was always, "If you want your friends to find you, text them."
With Time Machine, all of your check-in data speaks for itself.
All of that said, I was pretty impressed when I saw Foursquare's new Time Machine dashboard (sponsored by Samsung -- great move on their part, by the way, to brand the interface). It's awesome.