Man, I thought the Metal Detecting forum was a graveyard until I saw this place!
I've got some cool old stamps, mostly commems, some from as far back as the 1930's, from busted up plate blocks and such. I use 'em for postage. They're a cool way to dress up an envelope when I ship coins to somebody. Because the old stuff is ungummed, I got a lot of it for less than face value. I have to use a glue stick or rubber cement to put 'em on an envelope, but heck, they cost me less to use than modern stamps, so why not? I buy huge bulk lots. My local coin dealer used to be a big stamp guy.