Personally my Final Fantasy collection has one and my Rockstar collection has one. FF8 and Red Dead Redemption. The FF8 poster has Squall's face behind and above his gunblade with the insignia aflame and the RDR poster has a shot of Marston (and on the back is a map). The latter I have flipped over to show the map, but most of the time I display the Marston side.
Some of my posters came with the game, others bought seperately. Just always a fan of the advertising artwork. It's like when some people collect concert posters, I dunno. Just something I like to do.