Sinks and tubs have always been popular places for my cats. But when it comes to weird places, how about UNDER the rug? Or better yet (and I do not have photographic proof of this) Standing on a table right next to a lamp with your head up in the shade? Guess it was nice and warm.
I've also caught them laying IN the bookcase (I guess you're not allowed to have any empty spaces bigger than a cat).
Or how about sitting on top of the curtain rod? Maybe I can find that picture and have it scanned (but don't hold your breath, it might take a while)