Best Buy - Live Mobile Scan Map
Best Buy place QR codes on all their products. When a customer uses the Best Buy app, or any other QR code scanner, they are shown the product details for the product they have scanned. The Best Buy - Live Mobile Scan Map uses Google Maps to show the latest real-time scans of products in stores across the US.
The map uses the recently launched App Engine Channel API to update the map in real-time. The Google App Engine Blog has a good guest post by the developer explaining how the app was created. You can also play with a working demo on the channel-map-demo project on GitHub.
The map itself animates between the latest scans in Best Buy stores and makes good use of the Google Maps API styled maps functions to create a distinctive look for the app.