The Direct Connection - Driver, documentation, and guides for null-modem PPP connectivity. - http://www.kevin-wells.com/net/
PPPTCP - This is a peer-to-peer IP tunnel program that runs a PPP connection over an arbitrary TCP port. - http://www.devolution.com/~slouken/projects/ppptcp/
SLIP/PPP Homepage - Documentation for setting up a SLIP/PPP connection from your home computer to the Internet. - http://sunsite.nus.edu.sg/pub/slip-ppp/