I don't know if many people use coupons. I am but I use very select few coupons because of the way I shop. Thus I have ton of expired coupons.
So what I've found out is that you should send your expired coupons to overseas military families. They are allowed to use coupons up to 6 months after the expiration date at the commissary. Also they do not get coupons while overseas like we do in the US.
Anyway a good site to use to send these families coupons is The overseas non-profit coupon org. I just figured if you get the coupons and don't use them, mail them off. It could cost a $1 but it might be a nice gesture for those serving abroad.