Telescope Ring: 2012 - ThinkGeek
This product came out of a brainstorming session I did on my own to make 'real' super-power rings. I made a spreadsheet of powers, logos, sketches, & methods of implementing them, including: UV sensor, IR temperature sensor, Geiger counter style radiation detection, ultra-sonic distance sensing, butane lighter, etc. This ring is based on those folding toy binoculars you can find at science museum gift shops. The first CAD version I did actually copied the bezel aesthetics exactly, but we wanted to give it a more steampunk look, so there are a bunch of faux bolts & screw heads, but at least they're in places that make sense. I made a rapid prototype from powdered stainless steel using the online RP bureau I made the ring so that you could swap out the band for small, medium, or large fingers. The whole thing folds and telescopes open to the correct focal length and is intended to be used on the inside of a cupped hand.

Capt. Jules' Extraordinary Telescope Ring - $24.99