Actually, a while ago I was playing GT4 and I came up with what I thought was a pretty good idea. For the people who can't or don't want to shell out the cash for a wheel, there should be a control scheme where you actually rotate the joystick left/right in a steering motion to steer left or right, respectively. And allowing the joystick to recenter would straighten the steering wheel.
Feedback on this idea? Good/bad? I think it'd be great. Might take a little practice to get used to, but I think it'd be a better control scheme, especially for those picky about sensitivity. And there's just something about it that's more fun and satisfying than simply pushing the joystick either left or right.