A somewhat different thought that has been bouncing through my head for a while: what if one were to drill a couple small holes in their frame and route wires that way? (could probably be routed from the stem to the fork for speedometer, through the rest of the frame for more sophisticated lighting systems, etc). Having watched some American Chopper (not quite bicycles, granted), I've noticed that this is how they route most of their cables: through the inside of the frame. Would there be structural problems with that sort of thing?