Not exactly a website, but Google Earth FINALLY added Elevation Profiles to the latest version (5.2) a couple months ago. Google Earth has always had elevation information embedded since the first version, so it baffled me that they took this long to create graphical elevation profiles. So it's pretty nice to finally have them.

Another tip, if you have a route in Google Maps, you can click the "Link" link, copy that URL, paste it into your browser bar, append "&output=kml" to the end of it, hit ENTER, and the route will open in Google Earth. (This may be necessary because you still can't do the kind of detailed route-modification in Google Earth that you can do in Google Maps)

Neil