This is pretty cool actually – check out flashearth.com, which is a flash-based interface into the google and microsoft map data. It generally runs a little smoother than the dhtml-based interface on google’s site, and more importantly it lets you switch dynamically between the datasets. This is a really handy and time saving feature. I hope the developers keep enhancing this, it could easily become my default interface into the map data if they get to feature parity with the google and microsoft sites.