Not enough mAh, but under the 'what will they think of next' category.
ZNTER S19 9V 400mAh USB Rechargeable 9V Lipo Battery
Also take a look at the 'Frequently Bought Together' line below the main ad. Looks like they have AA and AAA as well, plus some nifty multiple device charging cables.
I must stop looking at all this stuff!!