Jolouis:
That's what I was thinking of, and it doesn't look terribly complicated. Also, a design such as that would work nicely with the N810's layout, as one could easily take a right-angle phono plug and fabricate/kludge a covering for it and the LEDs that wouldn't get in the way. I'll take a better look at that patent in a little while. I'm not up to the software side of things, but I could definitely build and test the actual hardware; I should have everything needed on hand. *checks parts bin*