PPP

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/

simpleppp.html
Simple PPP
http://www.animats.com/simpleppp/simpleppp.html

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/

Trumpet Software International
makers of Winsock software.
http://www.trumpet.com.au