I just benched my old Shoei after 6 years, and bought a new one. I didn't drop it or crash it, just think that it's cheap insurance to believe the manufacturers when they say replace after 5 years. Not trying to open that discussion.
But what to do with the old one? Seems silly to toss it in the garbage can. I could hold on to it in case someone wants to take a ride with me, but I can't very well put a helmet on my passenger's head that I wouldn't wear myself. I'm certainly not going to sell it or give it away for the same reason. Does the manufacturer want it back for some type of inspection, or degraded crash test? Should I start a shelf of old helmets (can't see my wife really going for that)? Make it into a clock radio? What do you guys do with old lids?