Here’s an interesting Google Maps implementation: Flood Maps.
What if the sea-level where to rise? .. Because the polar ice-caps are melting at an alarming rate … Would you be able to keep your feet dry? Now you can find out for yourself. (And maybe decide about that piece of real-estate you’ve layed your eyes on. ;-))
As a resident of The Netherlands this is all old news. As I have had virtual wet feet all my live. But still it’s a nice *cough* mashup.