None of the first four urls I randomly tried slashdot, ibm, dell, ycombinator have AAAA records.

IPv6 is not here and won't be for a long time. While v6 may be better in some circumstances, it is worse in others. I'll be keeping my offices behind NAT routers thank you!

http://sixy.ch/ has a nice public database of V6 ready sites and a tool to check/add

I like it. You should also add checks for ipv6 glue records. I advertise ipv6 dns servers but I do not yet have glue, so you still need to connect to my dns servers over ipv4. According to your tool I just have to convince google to add AAAA records to their MX targets and I'm set, but I'm not :)

Thanks for the suggestion.. I added a few more DNS-related checks. I think I have the tests/logic right but please let me know if you spot any errors.