The criminals in your midst!

It could stand a redesign, but I think the "Neighborhood Watch" feature on [1] is a smart, if also alarmist/fearmongering/fascist use of the mashup - you type in your address, it shows all the people with criminal records living near you, with an icon system that details the nature of their charge(s) - behavorial/theft/violent/traffic etc.

Similar idea on a larger scale - [2] - lists the terr'ist activities around the world, with an interface that resembles nothing so much as a geocities page circa 1997, brimming with animated GIFs.