probably want to add SSTP to your list. It's an SSL certificate based VPN from Microsoft (primarily) that is great at punching through firewalls without any additional port settings. I just setup one at work.
PPTP
IPSEC
SSH/SSL
L2TP
OTHER
Thanks halcyonforever.
I have not heard of this protocol before. Is that automatically in the likes of windows 7 / server 2008?
Basic Math:
1 + 1 = 2
1 * 1 = 1