.arpa, rDNS and a few magical ICMP hacks (sdomi.pl)
Through Project SERVFAIL, I became aware that there are a few individuals, not just ISPs, who host their own in-addr.arpa. and ip6.arpa. zones. It never occurred to me that I could ask bgp.wtf, my beloved ISP, to delegate me a zone like this - until one faithful late-night chat.ARPA zones are usually totally out of reach for individuals, so I was absolutely hyped when one of our netadmins agreed to delegate me the ip6.arpa. zone for my whole /48 IPv6 range.