Curtain rod to hang decorative items; could use this and switch out decorations for the different holidays/seasons.
Vinyl cuts with curtain rod to hang pics. Much better than drilling multiple holes in the wall, and you can easily vary heights of frames so you can switch your arrangement up.
Great idea from Miss Mustard Seed for making a template when hanging curtain rods. I would mark both sides and check to be sure they're level before drilling though. Not all windows are perfectly level - especially in older homes.