The Tell-all telephone  

Der Spiegel has a great little animation showing some of the data trail your phone leaves behind over a period of time - Tell-all telephone. Obviously a good tracking system would supplement this with data from your online activity (web sites visited, emails etc), your financial transactions, the locations your car goes etc - I imagine those who track everyone's comings and goings have a better memory of what people have been up to than they do themselves.

Green party politician Malte Spitz sued to have German telecoms giant Deutsche Telekom hand over six months of his phone data that he then made available to ZEIT ONLINE. We combined this geolocation data with information relating to his life as a politician, such as Twitter feeds, blog entries and websites, all of which is all freely available on the internet.

By pushing the play button, you will set off on a trip through Malte Spitz's life. The speed controller allows you to adjust how fast you travel, the pause button will let you stop at interesting points. In addition, a calendar at the bottom shows when he was in a particular location and can be used to jump to a specific time period. Each column corresponds to one day.