Is there a "alternative" way of doing kvm-over-IP

Buying the hardware boxes sounds pretty attractive, but I wondered if any industrious open sourcers have come up with anything that any NANOG-ers have come across that would do something similar to what the Dell 2161DS box would do. I realize we would need a server with some cards in it to terminate the connections and then some cards to go in the boxes, we just need a bit more density than 16 ports. Tia -Drew