Make little paintings. Or, make cards that can be hung as art above someone's desk.
You could make them in to keychains, cut them into pieces to make a mosaic, or use them to mix small bits of paint. Cut out the centers, paint the "frame" and sandwich a mirror between two of them. Use them as covers for mini books?
I made A pair of earrings out of them so far, and also some really cool charms, stay posted I will add pictures later!