One of the coolest things about the recently released Windows Live quickapps is the demonstration of a silverlight video showing someone riding around London on a bicycle, with the rider's position being plotted on a Virtual Earth map as the video plays.
The developer of the Quick Apps, Rob Blackwell (who will also be at our Mix:UK 07 event talking about how to use the Quick Apps just btw), has posted an entry on the Quick App forum talking about how he did this.
Worth taking a look if you can think of scenarios that might benefit from this kind of map/video interaction. If you want to see the application in action, take a look here, select the "London River Thames" ride on the left hand side, then click the "Bike Cam" button. Switch the map to birds eye view for best effect.