I have one of these ($8.97 @ Fry's) and it allows me to fold my normal size usb drive up at an angle into the corner of the back wall of the storage area.
Belkin Flexible A-A M/F USB Adapter
I also bought a couple of these for $9.99 each from Target. When inserted into the USB port, they only stick out about 1/2 an inch. I haven't decided yet if I want to swap these out for my normal size USB drive since the normal one holds twice as much (8GB vs. 4GB). I suppose I could just buy a larger MicroSD card and use that in this micro USB adapter instead.
Dane-Elec 4GB 3-in-1 Micro SD Card Bundle - Black