Is there a list of, for example, registrars, etc that are IPv6 friendly and ready?
Sixxs has a link on their site
http://www.sixxs.net/misc/coolstuff/
Sixy has a website dedicated to listing IPv6 compatible sites
http://sixy.ch/
EDIT:
Re-reading your question, I think this link might be more appropriate
http://www.sixxs.net/faq/dns/?faq=ipv6glue
I know from personal domain experience, that GoDaddy will work, as will Network Solutions (but you have to prod them a lot and during West Coast business hours).
GKG.net has all the services necessary to get you through all he.net certs, though their interface isn't the easiest in the world.
I had to leave EasyDNS because even though I was in their IPv6 beta, they didn't have any support for glue records nor v6 NS records in the root.