Personally, I think all fans should be fitted with shock collars that are calibrated to the amount of noise the wearer is making. 30 seconds of silence = a jolt to the neck. If the decrepit old bastards can't take it, give their tickets to people who are vocal.
One entertaining half-time activity would be to take an old geezer out of the stands and force him to try field goals. If he doesn't make it, an iPhone app lets the crowd give him a zap.