This is old, but still may be usefull. I now use openvpn.

tunbridge is a simple tool that steams data in and out of a tun network device.

I have successfully used it for a high latency, secure, simple, simple, simple VPN.

mkfifo $TMP
/usr/sbin/tunbridge tun < $TMP | ssh -C $1 "/usr/sbin/tunbridge tun" > $TMP &
ifconfig tun
route add -net gw
This ignores the appropriate ifconfig and route commands for the other end.

I'm sure there is a better way to do this, but I could not get tinc or openvpn to work. It could probably be modified to operate with the tap device and act like a hub instead of a router.