War 2.0
This mashup is clever. Via John Musser's ProgrammableWeb:
"The First MMO Real Time Strategy on Google Maps. Take over the world in this real time Risk-like game based on Google Maps."
Sign up is pretty painless, but a problem finding players - you need a minimum of two, so you could end up hanging around for ages to pair up against some competition.
(Btw, nothing here that couldn't be done with Windows Live Local...here's the Virtual Earth Dev Center).