What can the USB port that is not connected to the Toppy be used for?
Since you haven't had a response I'll give you a related comment. The slug (NSLU2) has 2 USB ports and e.g, you can connect the second one (via a usb to serial adaptor) to the toppy serial port for TAP diagnostics etc.
its pretty much useless
but you can charge your ipod with it.