Good way to redistribute heat in the house?

I live in a small rental duplex and naturally it stays freezing downstairs and an inferno upstairs. It doesn't help that the air intake is at the top of the stairs so all the heat just goes right up the staircase. Is there a way to situate a fan to blow the warm air back down? Do they make ones to mount on the ceiling for this purpose? There's no place to hang a regular ceiling fan on the stairs, without risk of decapitation. :)