Chuck, I'm sorry you have to go through all this. Reverse DNS lookup usually doesn't work with attacks like these because those who are curious enough to try the attacks are also good at hiding their tracks. I think a lot of people misunderstand why things like this happen.
Do you ever get satisfaction out of experimentation and tinkering to make something really cool happen with your reefs? You know... almost like conquering aptasia, or something. It's the same with hackers. They'll tinker just to see what happens, just for the sake of knowing they "beat the computer and found the weakness." What they don't take into consideration is that there are hundreds (thousands?) of people on the other side of that attack who have their enjoyment taken. So they'll find a known loophole or programming error in the software we use to run this board, and start attacking every IP address out there with a particular action. Only those IP addresses with that software and without the loophole corrected (a revision may not yet be out, at that time) react to it, and are shut down. If you're really that interested, look up "war dialing" or "port scan" for the basic idea of their MO.
All that aside, here we are on the other side. The attacks are coming from somebody who's never even heard of RF, and will never see this site. Chuck, I've actually taken notice to just how good of a job you do of keeping current on all the vB updates. Thank you for that! The vB board I run is on the same host as you, and we've had problems with them, as well. But... that's what comes with having the best price around, I guess. I'm assuming you're on a dedicated server, or at least virtual dedicated, right? Other than that, there's probably not a whole lot you can do besides take it in the shorts and deal with it.
Thank you again for doing such a great job running this site.