Not sure if everyone has seen this or not, but in the past, the Detroit Tigers have accepted donations for certain players for autographs on your trading cards. Each player that was participating had a specific price associated, and you could mail in a card. This year, the Tigers have custom cards made by Topps for those players participating, and you can purchase them online.
http://detroit.tigers.mlb.com/det/co...s-for-a-cause/

Players participating:
Daniel Norris
Matthew Boyd
Ian Kinsler
James McCann
Jordan Zimmerman
Justin Upton
Michael Fulmer
Mikie Mahtook
Nicholas Castellanos

Just wanted to share, prices range from 15 to 25, and it goes to the players selected charity.