Walmart has several new videogame Reservation Cards out that are actual gift cards! They are affixed to plastic 4.5 x 6.25 inch backboards, and cost $5 to activate, but the cards themselves can be used anywhere in the store. Our local Walmart had them on an endcap in the game section, plus there were more cards behind the locked glass case along with the rest of the games.
Here is what the Halo 4 card (0612 31) looks like: