The Cartography and Geovisualization Group at Oregon State University has been experimenting with ways to improve web mapping. An OSU summary page explains the current situation:
"Today's web maps (such as those by OpenStreetMap, Google, Bing, or Yahoo!) have two major shortcomings.(1) They use the Mercator projection for all scales and for all locations, and(2) they only provide pre-rendered views for a series of predefined scales."