JohnnyMac just posted a review of a combined single 18650 power bank and flashlight from Powertac, their E8. Four modes from a 1 Lumen firefly mode to a 388 OTF measured Lumens high mode. Not cheap but the highest power light with integrated USB power supply I am aware of. Of course with this combination the light is not limited to what a USB port can provide as the port is an add-on to an 18650 powered flashlight.
Here is the link to the makers web site. Not on Amazon yet that I could find.
http://powertacusa.com/index.php?route=product/product&product_id=241