Microsoft Research have released MapCruncher This looks like a great tool for doing georeferencing of data to Virtual Earth data, and then creating a mashup that you can easily publish on a web site. Its starting to introduce some concepts that previously have been the realm of GIS Proffesionals to consumers who want to build simple mapping sites and shouldn't have to worry about the fact that Virtual Earth data is in a mercator projection,or that their image map is not correctly georeferenced.