In any contextual palette where there is a numeric value field, it would be nice to have the respective MouseScroll Up to increase value by 1 and MouseScroll Down to decrease it. You can also throw in a Shift Modifier to increment the value by 10.
Many people are already used to this behavior from Adobe Products.
*Current Speed-bump - Increasing the value of Rotate or Slant (in palette) by keyUp or keyDown disables the window and you have to click it again in order to increment again. This behavior is not noticeable in Scale field box.