They're for usb-devices (duh!). It's standard usb-port so you can use any usb-device with a ps2 granted the software supports it. For the games that support keyboard and mice for example you can just take them from you pc and use 'em with a ps2. Another example: one day we noticed that my friends Logitech steering-wheel (pc) looked exactly like the ps2-version except color (and the names of the buttons) so we popped it into my ps2 and it worked like a charm with Grand Turismo 3. Granted, it was a little harder to use as the buttons didn't have the X, O, etc. markings but it worked fine.