The league shirt I mentioned above came from FGW. Not sure whose idea it was, but the front has the normal league logo (black shirt) and the back has a playfield resembling Space Cadet pinball in purple, teal and yellow colors. Another league logo below the playfield. Only the FGW folks could make Space Cadet look awesome. Shirt is 100% cotton although I don't recall the brand.
Put me down for one of those shirts with pentagrams down the arms. Nothing says pinball quite like pentagrams. d;^)