I've never done it, but here's some places that you can look:
(From
http://www.usb.org/faq/ans5.html#q6)
Q6: How can I connect two PCs to each other with USB?
A6: You need a specialized USB peripheral known as a USB bridge (sometimes called a USB to USB adapter) to do this. Anchor Chips and e-Tek labs, among others, make USB bridges.
http://www.3com.com/products/usb.html
http://www.easylinkusb.com/
http://www.techadvice.com/help/Produ...etAdapters.htm