At the office, there's a wonderful, magical area we like to call the Free Table. Some folks drop off stuff they don't want and some folks find stuff they do want, and the circle of life continues. It was on one of my five daily trips to peek at the free stuff that I found this:

And tried desperately to figure out what it was by placing on my hand it in different stages of dissasembly from multiple angles and taking pictures:

Luckily the piece was stamped with a name that rang a bell: J.A. Stein, maker of kick-ass bike tools. I even asked Problem Solvers bike mechanic therapist and French poetry quotist Ben WTF it was, but (as per the usual) he just gave me this look:

Turns out, as Ben later explained, this little doohicky is for removing a cassette lockring in an emergency-type situation. The splines sit in the lockring, the outer plate is secured by the QR nut, and your drive train works like a chainwhip. Sweet free table action!

Here's a better explanation:

"This tool secures the lockring from turning by locking it to the dropout so that when the cranks are turned with the bike in low gear the pedaling force will actually break the lockring free. It is designed primarily for emergency use. The tool can be used in reverse to be able to install the lockring as well."

http://www.jastein.com/PDF/cassette%20lock%20inst.pdf