Here's a link to the National Snow Analyses Center if you want to lay current snow cover over your Google Earth. Not much more useful than the snow cover website itself, since you have to download a new KML each time you want it.
This week, my work sites were talking about this new terrain feature in Google Maps. Pretty is a good word for it. Somewhat useful for planning and visualization. Would be nice to see this imagery get into Google Earth too, though my work sites say it's going the other way. That GE will be gone in a couple years, with all the functionality being moved over to Google Maps, (allowing for easier display in our cars and phones?).