I bought a MintyBoost kit from Adafruit because I've got so many devices that charge via some sort of USB cable (4 different phones, multiple Sansa e200's, etc.) I meant to have my 2 daughters help me solder up the circuit board part so they could put their electric shop skills to good use. (See included Mr. Blurry Cam photos) But I just couldn't wait! Sorry girls.The device can output up to 500ma at 5v so it will charge devices that my lame car USB charging adapter won't / doesn't. Apparently there is a low power USB spec that will output up to 100ma of current and a newer higher output spec.
I've included an action shot of the charger attached my Sansa e260 (booted into Sansa's firmware, which I only use for transferring files since my current version of Rockbox doesn't support full USB functionality yet). If you look closely in the lower left of the screen, you'll see the charge indicator on.
I really expect I'll get some use out of this for my T-Mobile G1 which is a big battery pig if you turn on all the wizzy extras like satellite tracking. A pair of recent NiMH AA batteries have about 2500ma capacity so should be able to charge up the G1's 1100ma pack at least a couple of times before they drop too low to push any more electrons over the USB charge cable.
