1 rotor engine.
 

Sorry, dont know if its in the right section....

Does it exist? Has anyone ever made one? Any pics?

I guess it would be able to push out 100 hp atleast considering the RX-8 has 255 with 2. It would make a great economic car since the mpg would drop considerably. 7L/100km?
Mazda could make a second smart...or am I retarded?

A couple of years ago, there was one on www.atkinsrotary.com

Some go-karts are using them.
They are centrifugal clutch setups on a shifter kart chassis. They make about 45-48 horsepower and are very fast, almost as fast as a Stock Moto shifter kart and perhaps even ICC's. The great thing about them is that they literally run forever while all other (2-stroke) fast kart engines need be torn down fairly often to have the top end done and sometimes, though not as frequent, the bottom end too.

The problem is that there is no class to race them in as of yet.

http://www.karting1.co.uk/wankel-kart-test.htm
http://cometkartsales.com/store/engine/aixro.htm