WebGL Earth is an open source 3D globe that runs inside a web browser. It is based on WebGL which is currently supported by: Mozilla Firefox 4 Beta, Google Chrome 9+ and WebKit nightly. The project homepage is located at www.webglearth.com. For a quick preview, the developers have recorded this video:
There should be no data shortage when using WebGL Earth. It can use tiles from OSM, Bing, CloudMade, MapQuest and your own tiles from MapTiler, Mapnik, TileCache or GeoWebCache.