Dear Gamers on this List,
A solution to the 'gamers' issues with VPN's might be Hamachi.
I've been using it for a while and it serves me fantastic.
(It's not only for games, it just supports broadcast over VPN !!)
If interested, take a look. It's not open-source though and that's a bit of a shame.
It host to host, and not net to net, and only supports up to 16 clients on one
vpn, but there are some vague promises that this will be increased.