great question... like to know myself too.
i have N7 (getting rooted soon); and a rooted S3 on TPR ROM.
ordering the OTG cable and a flashdrive.
side note: (I can't have her with more storage capacity than me, after all
why do you need this? your S3 can use microSD cards. that is faster and less wear&tear on that usb port.
i have not tried this.. but you can hot-swap the cards when the phone is on.. just have to unmount and remont the cards each time.