I've used the CyberPower 420MP battery powered usb hub on my Zaurus C1000's USB OTG port. It runs on 4 included rechargeable AAA batteries and can also be plugged into AC to charge with a *not* included AC adapter. It can also charge from a desktop's USB port.The bad news: It's not powerful enough to spin-up a 1.8" USB hard drive. It's really close but even if it worked I'd be worried about it running out of juice during file transfers. It *is* powerful enough to run a USB flash memory stick that the Zaurus refused to work with when it was directly plugged in. Anyways, I guess it's buyer beware, but it only costs ~$20.

-John