Personally I think a large-scale Starcraft MMORPG would be the most kickass shit ever.

Imagine picking a race (sort of like RvR in DAoC), and becoming a zealot, marine or hydralisk.. and as you level up or whatever, you become a stronger unit, eventually becoming a siege tank or something, and having massive battles like the original SC but everyones controlling thier own unit instead..

I'd call it.. "Korea Vs. The World"