http://www.sixxs.net/main/ (www is required, the site isn't perfect but it works)
I currently have two tunnels (one to an out of house server & one to my house), a subnet for my house (I've tested it, I can ssh from an external server directly to my in-house computers without any port forwarding). It adds a little latency (since you have to go through some other router before reaching the ipv6 part of the internet), but not too bad.
CowboyNeal reminds me
Disturbing news indeed."