My feeling has always been there has to be something more than "I was here!" to make it compelling. For the most part, few people really (or at least SHOULD) care that you were just getting a coffee or in line at the water park. How can "your" presence at a particular location be compelling to me?
I've been working on a project (and realizing how dreadful my self-taught coding skills currently are) that uses that innate tendency we have to associate our identities or personalities with the places we frequent, and our desire to communicate with others.
As a side note, if anyone is looking for an interesting mobile/web app project to get involved with, I'm now looking for someone better than me with Javascript ;)