Tribute cards pay homage to the best baseball card sets of all time.  It's a way to celebrate old designs with new players.  As well as new designs with old players.  And vice versa.

How does it work?  Well, I start by finding a set that I like.  From there, I get a high quality scan of an existing card.  Then, I take that scan and break the card apart into Photoshop/Pixlr/Vectr/whatever layers.  At that point, I create a new baseball card that has never existed! For instance, here you can see the 1952 Topps design with Brad Hawpe.