I've featured an SP card on the blog before along with the revelation that 'SP' didn't actually stand for anything in particular. It was a publishing name for Upper Deck that covered other sports besides baseball. Over the years it spawned offshoot ranges as well.
Card Number 316: Upper Deck SP, 1994; 130
Card Number 317: Upper Deck SP, 1995; #105
Upper Deck released another SP range in 1995 - SP Championship!
Card Number 318: Upper Deck SP Championship, 1995; #90
Tony signing stuff photo!