I still haven't messed around with the custom settings on the dial, but under the custom fuction there are 4 different menus, inside those menus there are a min of 3 settings you can change, the most is 13. Every button, knob you can change to do different things on the actual body of the camera.
Then you still have picture styles that you can change.
I'm sure there's more but whatever. I do know that this is a huge step above any 30d/40d or rebel I've shot with. I haven't had a chance to shoot a 5d/mkII or the 1d series bodies.