The Mappish project
Mappish is an app for Android devices that records your movement over time and lets you visualize it in a number of ways. The main use is a projection of the geolocation data on a map.
This project falls in the cathegory of me trying out fun things. And there are a few fun successfull things I learned about gaussian blur and clustering. If you can find anything of use in here, by all means, use it. The entire project is open source under Apache 2.0