Bolts in bulk? Anyone done this? What sizes?

I am a fastener hoarder. When I go to the junkyard, I scavenge any nut and bolt I can find. My local hardware store sells nuts and bolts by the pound, and once a year they have a 40% off sale. I load up on everything during the sale. I can't even guess how many times this nut&bolt stash has saved my bacon during a late night wrenching session.