Check out this crazy midi project by Charles Gallant, he retro-fitted a new bridge with midi pickups and all the necessary circuitry and of course the 13 pin midi output jack which by the looks of his Flickr set took a bit of extra routing to the body and lot of wiring! If you watch the video you will see each note gets plotted on a grid depending on the pitch and it appears that the size of the animated box is dependant on velocity. Now this kind of thing is by no means new but for someone to write an application like this just for fun is pretty cool. I imagine Charles will develop the idea and apply it to more interesting scenarios such as a Guitar Hero style game maybe or a more intricate visualisation tool that can be used for performance? Who knows we will have to wait and see.