I used foursquare for about 3 weeks. I comment on HN because I want people to start recognizing my name. I post to twitter because I want a large follower base I can bounce ideas off and tell about things I'm working on. I answer questions on quora because there are a lot of wealthy, influential people on there and I want them to know I'm a developer trying to make his way in this world. The point is, I need to get something back from these services if I'm going to dedicate my time using them.

Foursquare gave me nothing in return. There's no value in being a mayor, and because theres only one mayor per location it's nearly impossible to maintain. None of my friends in town use it, so the potential value of finding out where my friends are and what they are up to at any moment is nonexistent.

I would use Foursquare if it would tell me if my buddy is going to the gym without him having to do anything. I would use it if it would actually keep track of the number of times I've bought a coffee at my favorite coffee shop so I don't have to keep messing around with those stupid punch cars that I lose every other week.

The first location based service that solves either or both of those problems will be the first one I use consistently.