First the hunt for cheap picture frames and mats. That means a Valu-Village trip!
Second, I've seen these stick on hooks from 3M. They have little hooks, and hooks as big as coat hangers. They are supposedly removable without damaging the paint. They make picture hanger versions of these hooks, how much weight can they hold, and do they wear out (i.., after a couple months, will my pictures be falling off the walls?), and how well do they deal with heat and moisture (for hanging pictures over the fire place and in the bathroom)?