Embedded USB Software

Maybe this tools will help you: http://www.jungo.com/usbware_embedded_usb_solution.html

It offers all popular usb classes such as Mass Storage, HID, Video, PictBridge, RNDIS and CDC.

Thumb drives or dongles are cheap, 2Gb for $15 at Microcenter. They are quite small and even smaller if you remove the casing.

Check www.ftdichip.com and also a good article in March 2007 issue of Circuit Cellar regarding these folks products. The have a device that is already configured for using memory USB devices from an imbedded controller.