Thanks

I actually think that a pretty decent Perl programmer could (or perhaps has, and i have simply not run across it yet, although i have been keeping my eyes on freshmeat.net and sourceforge both) write a CGI script to do the MAC lookup.
Of course, if we were gonna get TOTALLY next level, there would be a CP module to allow you to periodically search for duplicates...but then again...we can't always have EVERYTHING we want

I would be thrilled just to get it going for IP AND MAC logging on registrations and posts.
Our site has around 5000 members now, and the number of repeat offenders just keeps growing....with the log in required option now available, being able to check the MACs on registration and posting would be a pretty solid way of keeping out the problem children.