Ace modder Ben Heck has created a one-handed 360 controller mod that is impossibly sweet.
Check it out: This way, you can pull an Arenas and play yourself at Halo 3 and actually have a fighting chance! Or, if you're the drummer for Def Leppard, you can finally play games! Or, you can play your 360 and drive at the same time! Residents of Vernon, Florida who shot off limbs to collect insurance payments are in luck too! The possibilities are without limit.
The controller will first appear as a wireless model for the PS2/PS3, with an Xbox 360 version following. For more info, check out Heck's web site