Old QSL cards

Amateur Radio Weekly pointed me in this direction. 

Although I have not looked exhaustively at the site, it seems to be an extensive collection of old USA and Canadian  QSL cards. 

I expect somewhere on the net is a collection of old QSL cards from the rest of the world.  UPDATE: See http://www.qslcollection.co.uk/ .

See https://www.oldqslcards.com/ .