Inflightpower.com have created a new in flight charger which plugs in to the headphone jack found on most planes. The unit then uses USB to connect to your device (anything that can use USB to charge) and provides bursts of power.
The device stores energy from the headphone jack which takes 3 - 5 minutes (volume to be on full) and then stores that and allows your device to be powered for 1 minute and then the cycle repeats it's self. This is a VERY handy tool for those frequent flyers.
More information at inflightpower.com