A lot of people will run their air conditioner or a room fan if they don’t want to get too hot in bed, but also don’t wish to sleep with no covers at all. If the overheating problem is due to body heat trapped under the covers, however, why not just run a fan in the bed? That’s the idea behind the Bed Fan.
The Bed Fan device actually incorporates two fans in its base, which sits on the floor at the foot or side of the bed, drawing air from under the bed – so make sure all the dust bunnies are swept up first. In the case of beds that sit flush against the floor, the base can be swiveled 180 degrees to point outwards.

That sucked-up air is blown up through the adjustable-height, um ... tower(?), and then channeled out horizontally to end up under the sheets. An included backlit wireless remote can be kept beside the bed, allowing users to increase or decrease the fan’s output as needed.
Hot sleepers can get the Bed Fan for US$99.99, from Brookstone. A similar product, the much differently-named Bedfan, sells for $79.95.
Source: Brookstone via OhGizmo