Raste Pe -On Your Way
This a basic but interesting Google Maps mashup. The map uses the Google Maps API driving directions with the Twitter API to give driving directions with Twitter messages along your route.
The driving directions are presented in the normal manner, with the length and time of the journey and numbered directions. The Twitter messages along the route are shown with red map markers. If you click on a marker you can read the message and view who it was posted by.
I guess this could be very useful if it was combined with traffic information to give you real-time news along a route that you about to drive.