I was poking around in the trunk of my wife's 97 grand prix fixing the light in there, and I noticed beside each of the rear speakers were a pair of wires and a connector not going to anything. Now it's bugging me--any idea what these extra wires are?

Those wires are for the bose speaker set-up, which have both a 6x9 for lows and a separate 4" mid-range speaker.