Well, the good thing about both Crowdspottr and Fiestastic is that, unlike classic social networks (Twitter, Facebook, etc), even if only 1 user uses the service, it's already useful for him/her, as all data (events and friends) comes from Facebook.

Of course, being widely used (at least in a specific area) would bring extra benefits and more possible features, but I like that it's useful even to the very first user.