DNS reverse record

You could add a zone with Zonerunner, put a PTR record in there, make sure the delegations are in place and go wild with the records, but your ISP probably won't delegate their block to you if its not a big block of IPs, so they'll be the best place to start. Just request a new PTR for the IP with the value of the host.

Strictly speaking, your ISP could create a delegated zone for even a small block or even a single reverse record -- whether they'll do it depends on who they are.

if you do a dig -x "ip address" you'll see who "owns" that address space and figure out where you should get the PTR record added.