I cover a lot of high-tech gadgets, but here's a simple little accessory -- that even technically qualifies as wireless -- the Logitech Joystick for iPad (and iPad 2).
This is a clever little device that helps gamers better control the motion of an on-screen joystick or d-pad on the iPad, compared to trying to position your hand and thumb precisely at the corner of the screen.
Instead, this thumb-stick style game controller attaches to the corner of the iPad with two small suction cups. The coiled spring design then provides force feedback as you slide to the sides, and guides you back to the center position.
So for more precision in your game action, check out the Logitech Joystick for iPad, available for $19.99.
See my Portable Accessories Gallery for more on PC and portable accessories.
Find the Logitech Joystick for iPad on Amazon.com