This Spot is an interesting app. It touts itself as "part utility, part random reward, part (anonymous) geo-location and part social sharing" - all of which is true. However, it manages to do all that with a very simple interface. You load up the app, it geolocates you, builds a collage of nearby recent photos and asks you to track your mood at the moment (which you can then share). The results get better the more people that use the app near you - so, give it a spin and make sure to get others to use it as well!