Battlefield 3 this week. Every specially marked bottle of Dr. Pepper has a code in it that you can redeem on the official Dr. Pepper site, and that code will earn you special DLC for the game. This includes mulitplayer skins and a PlayStation Home avatar, to various special edition dog tags to display. You can see the dog tag choices above; they're especially meme-y for some reason, like a whole six wolf moon to Hello Kitty, and a Rebecca Black-inspired beer bottle opener.
If you don't want to shell out for the soda itself, you can get a free code through Dr. Pepper's website (though you can only select the content for one platform, so choose wisely). The promotion ends on December 31, so make sure you put them in by the end of 2011. And give thanks to the ever-lovin' gods of sugar water for the free BF3 DLC.