TomTom has added another API to its mapping and navigation solutions portfolio: Traffic Stats API. Traffic Stats collects data from over 450 million connected devices in order to provide historical traffic data. The data collected includes speed, route, travel time, segment, and more.
Take a look at MapCruncher. A very interesting new map mashup technique from the folks at Microsoft Research. It basically allows you to overlay any digital map image on top of a normal, zoomable Virtual Earth map.