A business acquaintance recently ran a contest together with Spencer & Broderick, a local promotional video producer, that involved finding beacons, kind of like indoors geocaching. The post also goes through how to use beacons in Titanium.
Actually, geocaching is an interesting non-pro application of beacons. Also consider e.g. orienteering, where you just have to be close to a station to become cleared, and of course the system behind it could collect data on each contestant and show status in real time.