I have rods that you put rings with clips on and I mounted the rod to the ceiling. They way they mount, they can go on the wall, ceiling or sloped ceiling (the other side of this room is sloped)
This is not the best picture, but the only one I already have uploaded to photobucket. There are three brackets (mounted where the ceiling joists are) so I can't slide the curtains all the way to one end, but I can slide them enough to get at what I need to get. Eventually I'm going to make quilted panels instead of using old curtains.