[44net] Making Packet Node with Pi ?

Hi there Is there a way to have a Packet Node with Pi (or any other small size solution that will not require a PC) ? If yes How do I connect TNC (serial port) to PI is the Pi support USB to serial external interface (like the profilic ones) ? Or (preferred) something can be done to do the TNC on Sound card (can be an External sound card that connect to the USB of the PI) Please Advice Thanks Forward Ronen - 4Z4ZQ jttp://www.ronen.org