Just found FlashEarth today, created by Paul Neave.

This Flash app uses map images pulled from either GoogleMaps or Microsoft Networks Virtual Earth to display it’s images, and lets you decide which server’s images to use. Once you find the location you want, just use the radio buttons in the top-left to toggle between the images used by either Google or Microsoft. That way you can make your own comparisons to see which version of the geography you like better.

Link: http://www.FlashEarth.com