Ruth de Vos stitched together some of the cutest world map cushions I've ever seen. And you should go see some more photos of them on her blog.
This is a great idea for any travel-themed nursery, even if you don't have the room to leave them laid out all the time. Stacked up in the corner with one of the more recognizable land masses on top still gets the idea across. And they're bound to make playing on the floor with the little ones much more comfortable.