sprint.net has a pretty nice one. Theirs isn't an IPv6 day exclusive either. Kind of amusing address for a telecom company...
For anyone else whose ISP doesn't support IPv6:
PING sprint.net: 56 data bytes
64 bytes from www.sprint.net (2600::): icmp_seq=0. time=156. ms
64 bytes from www.sprint.net (2600::): icmp_seq=1. time=151. ms
64 bytes from www.sprint.net (2600::): icmp_seq=2. time=153. ms
64 bytes from www.sprint.net (2600::): icmp_seq=3. time=151. ms
64 bytes from www.sprint.net (2600::): icmp_seq=4. time=151. ms
----sprint.net PING Statistics----
5 packets transmitted, 5 packets received, 0% packet loss
round-trip (ms) min/avg/max/stddev = 151./152./156./2.5
This is kind of nice pun indeed, thanks!
I use dead:beef and feed:cafe for my 2 small subnets on a /48 I got from he.net, because it's easy to remember.
Of course, if you really want to identify your allocation, setup reverse dns. To do it the easy way go to afraid.org. They offer a great free service, IMHO better than dyndns.
HE also offer a free DNS service now, considering you've already made an account with them.
Also: their DNS recursive server is whitelisted by google, so you can get YouTube videos over IPv6
I'm already using it, 2001:470:20::2 or 74.82.42.42, but I didn't know they did reverse DNS as well.
I'll think about it. For now afraid.org just works.
Here's some. Check the AAAA for:
www.facebook.com www.luns.net.uk www.cisco.com
EDIT:
I meant, check the literal IPv6 addresses that correspond to these hostnames. I'll put emphasis so it is more visible :)
2620:0:1c08:4000:===face:b00c===:0:1, 2a01:8900:0:1::===b00b:1e5===, 2001:420:80:1:===c:15c0:d06:f00d===
EDIT2:
And while you're at it - maybe enable AAAA record for your site and give it a whirl! (and come up with some more creative IPv6 addresses in the process!) Thanks to guylhem for reminding about this.