VPN using OpenSSH and tun(4) under FreeBSD
http://blog.brixandersen.dk/2006/10/23/vpn-using-openssh-and-tun4-under-freebsd/

 - pure ssh, no ppp

Setting up a VPN using FreeBSD
http://www.bond.id.au/~gnb/vpn/fbsd.html

 - ssh + ppp

VPN alternative: ssh -w
http://www.daemonforums.org/showthread.php?t=141

 - pure ssh, openbsd variant

VPN over SSH
http://bodhizazen.net/Tutorials/VPN-Over-SSH

 - linux

OpenSSH - True VPN
http://wiki.enigmacurry.com/OpenSSH#head-5f551cc91f938f56dfcd85b7829780b6df9bc303