Yeah, I have a couple of read heads put aside for this purpose, but I ran into trouble trying to design something that'd carry the weight and still work on a mouse. I think I'll end up gluing the optomechanical sensor to the bottom of the shaft, then gluing the outside of the bearing to a box (or trophy stand, if you're classy).
I'm also interested in anything that gets posted here.
Really, I only need it for scrolling. Maybe it'd be easy to make with a microcontroller instead of having to use an entire mouse.