Wait, I just realized that you probably meant the Road Map view? A lot of stuff doesn't show up on that!
Sometimes for the U.S. I wander along the landscape with the corresponding topo map open in another browser window. (If Google Maps would somehow integrate that - oh man!) By looking at the topo maps, road maps, & Satellite images all (sort of) at the same time, you get a much greater view of what's there... not a complete view but more info is filled in that otherwise you might never know about.
Islands 
Sometimes for the U.S. I wander along the landscape with the corresponding topo map open in another browser window. (If Google Maps would somehow integrate that - oh man!) By looking at the topo maps, road maps, & Satellite images all (sort of) at the same time, you get a much greater view of what's there... not a complete view but more info is filled in that otherwise you might never know about.
Have you seen MultiMap's interface?
Their aerial mode creates a semi-transparent area around the pointer that shows their map overlaid on the aerial photo.
Check this link out for an example:
http://www.multimap.com/map/photo.cgi?client=public&X=406000.68413737&Y=287000.060928519&scale=10000&width=700&height=400&gride=&gridn=&lang=&db=&coordsys=gb
That's a pretty nifty interface trick; it could use some tweaking though...