what about the massive ad system, that would enable you to advertise
eu in other games, that could be very cool. as a existing customer of massive i would have thought you could negotiate a discount too
and sal has a great point about london underground, and any other commuter system, thats a very good way to get the name promoted and to get some brand awareness
heres a company that specialises in london underground advertising
http://www.viacom-outdoor.co.uk/ukMedia/underground/