Every year at Comic-Con, the studios find new and interesting ways to promote their new and returning TV shows and movies. For the past two years, Warner Bros. Entertainment has used hotel room key cards as a way to raise awareness for some of their shows. Since the promotion worked in the past, they’ve just announced they’re doing it again and they’ve created five limited-edition collectible key cards featuring specially designed artwork for Smallville, Supernatural, V, Batman: Under the Red Hood and a DC Comics App. You can see what they look like after the jump. According to the press release, the cards will be used for 29,000 hotel room keys…meaning if you’re going to Comic-Con, you’re going to probably get one.