This isn't really "refraction," but the effect is so neat I had to submit it anyway. This is a picture of a mineral my mother got me on a trip to Nevada, unfortunately I don't recall what it's name is. Evidently there is only one other mine for this particular mineral and it's located in China. What makes the quartz(?) so unique is that it has striations in it which seem to bring whatever images are behind it to its surface. So if you run it across newspaper print, it seems that the print is actually printed on the top of the mineral. Hopefully someone in the comments will be able to shed more light on the subject...
Anyway, I put an old film negative behind the rock with a light shining through to get the image you're seeing in the center. It didn't come out as defined as I would have liked but you can still kinda make out the image (our kid in a cowboy hat.) This was set up on a stack of HDD platters and illuminated from the side with a MacBook Pro...
Canon 7D in AE mode
Aperture: f/4
ISO: 200
Shutter: 5 Seconds
Lens: Canon EF 70-200mm f/2.8L IS II USM with the Canon EF 25 II Extension Tube
-Joshua Winkelmann