The regular Xbox 360 controller is nice and all, but I wonder if it couldn't be made more... extreme. Ah, here we go. The Avenger is what I'm looking for.
This crazy contraption adds some strange levers that move where your push the main buttons, and it involves all sorts of sensitivity adjustments if you feel like you have to push down too hard on the shoulder buttons to toss a grenade or whathaveyou. Also, it looks absolutely absurd.
That being said, The Avenger comes with a money-back guarantee, so if you're curious and don't like it, you can always get your $60 back.