I also just ordered this micro thumb drive for $8.50 shipped/tax and might try Kenwood's music software for kicks.
I figure I can leave it in the radio and ignore it. I was slightly upset about buying the radio this morning, I didn't think to check if it had rear USB, I just wrongly assumed it did.
My previous cars, I ran the USB cable to glove box, or console for iPod instead of hanging out the dash. I "may" open it up and move the USB to the rear for that purpose.