It is my custom to use Amazon gift certificates at Coinstar machines to dispose of my extra coins, because in that case the coins are exchanged for free. (I have many extra coins, since I usually eschew credit cards.)

Wal-mart hosts many Coinstar machines, but I have yet to see one that will produce Amazon gift certificates. You have to go to Coinstars hosted at grocery stores for that. So, they have a contract with Coinstar that specifically mentions which firms may have gift certificates on Coinstar machines.

Who knows, this may be a boon for the grocery stores?