I'm ready to follow the local historical society, an environmental justice organization or two, perhaps an art-graffiti-watchers association - the possibilities are nearly endless. Imagine allowing background location tracking and notification for some layers. "To see the world through the lenses of my favorite organizations" would be a nice addition to the reasons why people say they use check-in apps.
This is a very cool idea! Actually not a new idea, (are there any), but a great method of delivering this.