TuneJuice - iPod Battery Extender extends iPod battery life by 8 hours
The Apple iPod's can run for a long time on batteries but, what if you need more juice? And you are stuck on an airplane or a bus with no battery chargers or power. That's what the TuneJuice iPod battery extender is made for.
Simply plug in the TuneJuice into the iPod docking connector, put in a standard 9V battery and you can continue to enjoy the music and videos for another 8 hours of additional playback. If your iPod is completely drained of it's battery, you will still get up to 4 hours of playback with the TuneJuice iPod battery extender. Of couse, you can carry additional 9V batteries for more playback time.
The TuneJuice works with pretty much any iPod with a docking connector and it's available for US$ 18.99 from Think Geek