Hack your 3G iPod's battery display...

Found this hack mentioned on both Mac OS X Hints and MobileWhack:

If you'd rather have your (third generation only) iPod display an actual value for its battery state (instead of the disappearing battery bar graph), just open the Terminal (with the iPod docked and available as a hard drive) and type:

touch /Volumes/your_iPod's_name/iPod_Control/Device/_show_voltage

Replace your_iPod's_name with the name of the iPod as shown in the Finder. Now eject, disconnect, and restart your iPod, and you should see a number in the top right corner of the screen -- on a full charge, mine was showing 474; I believe the maximum is 500.

Coolness!