http://aaron.birenboim.com/VNC/sshVNC.html

Start up the VNC server, and set an appropriate VNC password.
Open up a secure tunnel to this server with a command like:
     ssh -R 5900:localhost:5900 guest@boim.com
(Ask aaron for the guest account password, or use your boim.com account)
If you are not using a command line version of ssh (like a newer version of putty) open a connection to boim.com and set the appropriate port forwarding options. On putty I think its something like "-R 5900:localhost:5900".

Now, people with VNC clients can access your machine with commands like:
ssh -L 5901:localhost:5900 guest@boim.com
vncviewer localhost:1 &