Signed 1865 Ulysses S. Grant carte de visite photograph by Brady & Co. — currently up for bidding at Heritage Auction Galleries (the same place that sold those D.B. Cooper $20 bills I posted about before — I'm getting their catalogs now and I'm amazed at the things that come up for sale).

A carte de visite was a standard 2.5" x 4" albumen print patented in 1854 by a Paris photographer named Andre Adolphe Disderi. Their popularity spread quickly — people would get them made and then trade them with their friends and people they met.