Edit: Those of you coming across this post by googling for 'Sixxs rDNS' should note that Bytemark's DNS service isn't free unless you already have a server with them, but there are a number of free alternatives out there.
With IPv4 address space exhaustion practically upon us, I decided it was high time my house got IPv6. This is quite easy to do even if your ISP, like ours, doesn't support it natively. Get a Sixxs tunnel, apply for a subnet, set up radvd on the Linux box behind your sofa (you do have one, right?) and there you are.
Even Windows XP can be trivially prodded into IPv6ing itself up, and my router seems not to mangle the radvd broadcasts so even wireless clients can have v6 if they support it.
What really impressed me, though, was what happened when I wanted to set up reverse DNS for my new Sixxs subnet. I've been assigned 2a01:348:1af::/48 and the Sixxs page tells you that you'll need your own DNS server to host the necessary records. I don't run my own DNS; I use Bytemark's content DNS service.
I wasn't expecting Bytemark to support adding rDNS records for random IPv6 /64s, however as it turns out, once you work out what the TinyDNS file needs to look like:
# IPv6 rDNS authority for Sixxs subnet 2a01:348:1af::/48 .f.a.126.96.36.199.188.8.131.52.a.2.ip6.arpa::a.ns.bytemark.co.uk .f.a.184.108.40.206.220.127.116.11.a.2.ip6.arpa::b.ns.bytemark.co.uk .f.a.18.104.22.168.22.214.171.124.a.2.ip6.arpa::c.ns.bytemark.co.uk # Machines in the first /64 (home network) 6router.ipv6.dnorth.net:2a01034801af00000000000000000001:8640
... it Just Works:
$ host 2a01:348:1af::1 126.96.36.199.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.f.a.188.8.131.52.184.108.40.206.a.2.ip6.arpa domain name pointer router.ipv6.dnorth.net.
Nice one, Bytemark!