I'm looking for a battery cradle with mini usb

[sorge]

Right now I'm looking for a battery cradle, that I'll know for sure will charge off mini usb. I use the hell out of my phone, and I do have a car charger, but it would be great if I could find a cradle and battery that charge off mini usb. I've seen some real cheap ones on ebay, and some more expensive ones, but I want to know for sure.....only problem I have so far is the damn battery life....I text and make a lot of calls with web usage.