EARTH DEFENSE FORCE 2017 (XBox360)- An amazingly fun (especially with a friend) shooter that lets you go ape on waves of giant alien robots, giant spiders, giant ants, giant dinosaurs, giant cyborg dinosaurs and of course, alien ships... all being taken down by a single (or two) dude(s) with a swivel hip of epic proportions and ever upgrading weaponry. Cheap, relatively unknown and completely awesome. There's also a versus mode, three levels of difficulty for all missions and it's a steal for like, $10.
THE OUTFIT (Xbox360)- Very fun and entertaining third person war game, where you take control of one of three characters, lead a platoon of 4 guys into battle, calling down support in the form of turrets, vehicles, replacement troops, etc, on the fly, with the points you acquire through defeating targets or capturing objectives. You also improve your characters individual specialized weapons as you advance. Also co-op, so you and a friend can split screen them evil Nazi's.