Yea I am full of requests, unfortunately due to the nature of my employment I cannot contribute code to this project without approval and that is highly unlikely, even though I only use m0n0 personally.
Using IPv6 tunnels from Hurricane Electric you need to update your endpoint IP address when your WAN IP changes.
They have an API that allows you to update the endpoint IP here:
http://ipv4.tunnelbroker.net/ipv4_end.phpIt would be quite easy and nice to have an option in the Dynamic IP section that simply fetched that URL with some values saved in the config when the WAN interface changed.
A more robust implementation might be to set the WAN IP as an environment variable and give a text input box that allows some custom commands/scripts be executed when the IP changes.. this would allow m0n0 to work with tunnelbroker, freedns.afraid.org, and open other possibilities like sending a signal to a monitoring server to fire-off a notification email that the IP changed.
Cheers,
-R