We liked Griffin's previous version of the PowerJolt, which included both a car charger and USB dock-connector cable for $25. Griffin recently updated the PowerJolt, and the new version offers more functionality at a lower price of only $20.
The PowerJolt's adapter -- noticeably smaller than its predecessor -- plugs into your car's accessory ("cigarette lighter") jack and provides power to any device connected to the the PowerJolt's USB port: You can charge an iPod shuffle by plugging it directly into the USB port, or you can charge a 4G or later full-size iPod, an iPod mini, or an iPod nano using the included 4-foot USB-to-dock-connector cable. In addition, the PowerJolt includes a USB-to-mini-USB cable; this cable can be used to charge an iPod that's already connected to one of the company's dock-connector iTrip FM transmitters, which provide a mini-USB pass-through port.
A status light on the adapter indicates charging status: yellow-orange when your iPod is charging, green when fully charged. A nice touch is an accessible 2-Amp fuse that protects your iPod from surges and can be easily replaced if necessary.
In our review of the previous PowerJolt, we suggested that its $25 price was justified by the inclusion of a dock-connector cable similar to the one Apple sells for $19. With a better design, lower price, and an additional cable, the new $20 PowerJolt is that much better a bargain.--Dan Frakes