my favorite glue to use with these is aquarium sealer (left over from modifying a fishtank to house 2 male bettas) sticks like nothing else, and the vinegar smell as it cures is less offensive than most stinky glues.
so yeah, pictures!
these are all from my original doodles (i have obsessive respect for copyright law) shrunken to appropriate size on a color copier. I also made a nifty image-tester, to see if a certain picture would be good for a magnet before gluing it down I took an index card, and punched a 1/2" hole in it. then I put a litle square of cellophave (from a CD wrapper) under the hole, and glued a marble on top of the hole. saved me from wasting several marbles already on images that don't look very good magnified.