Toggle iPod Battery Status is a tool to switch between the two options (including one hidden option) for iPod Battery Status display. Your two options are the default "Icon" view, showing a picture of the battery with the dark part filled to indicate how much current you have left. The other view is a "Numeric" view. It shows a number between 0 and ~500 to indicate your voltage. This software automatically detects which setting you are currently using and switches to the alternate method.
This program works, but but my ipod said it was outta batteries when the meter said 125... This made me really mad becasue this program doesn't work rite. Otherwise it would be cool if that would be fixed
Here's how to do it for free.
This only works on 3G ipods.
Here are more ipod hacks, including where this one was found.