What i am making here is a USB lock with smartcard key. The idea is that a phonecard reader made with a PIC micro will be able to store a number of different phonecards into memory. Whenever one of these cards is inserted into the slot, it will activate a 4-ports USB On/Off switch. If the card is removed, the USB ports will be de-activated.
Lock USB ports via a PIC-based smart card reader - [Link]