The PowerMonkey Explorer is a nifty battery charger because there are three ways to charge the battery.
You can buy one for around $100.
Maxiumum reserve power:
All iPods – 40 hours
Cellphones 96 hours standby
Digital cameras – up to 1600 extra photos
Two-way radios – 24 hours
PSPs – 5 hours
MP3/MP4 – 6 hours
PDAs – 48 hours
Included tips:
LG Chocolate
Micro USB
Samsung G600
Mini USB
Mini Nokia DC 2.0
PSP & digital camera DC 4.0
Female USB
Sony Ericsson wide 750i
iPod charging
Nintendo DSi
Retractable USB charging cable