Now this is cool.
It's a fan without blades that works by induction. OK, there is an impeller in the base that sucks air up, but it blows it out through the edge of the ring. The motion of the air over the airfoil sucks more air from behind to follow it (induction), and as it all blows out, more air follows that air (entrainment). The upshot is 15 times more airflow than the impeller pulls from the base. $300 bucks though, and I'd say the impeller is a bit whiney.