Dont forget, make your website accessible via IPv6 and submit them here:
- http://isoc.org/wp/worldipv6day/
- http://www.ipv6forum.com/ipv6enabled/ipv6enable.php
- http://look4ipv6.appspot.com/ - (Update 7th March 2014: doesn't work any more)
It might be worth considering to make your already IPv6 enabled website accessible only via IPv6 on the World IPv6 day... join me in!