If I remember right, back from reading about some previous legal cases, there's nothing that stops anyone from 'camping' on a domain address for as long as they want (or at least until their registration expires) whether they use it or not. The exception to this (at least in the U.S.) is when a name they have registered is identical or substantially similar to a trademark, service mark, or other registered mark of an individual or corporation. In those cases, and where the current owner doesn't have an equally good reason for for wanting that domain, the current owner can be forced by court order to hand over the domain to the protesting entity.

So, someone that had glommed onto McDonalds.com early on could be forced to hand over the domain name to the McDonald's Corporation. However (and I've seen cases along this line) someone named Timothy Horton could not necessarily be forced to hand over his registered site, TimHortons.com, to the Tim Hortons restaurant chain, because he has a valid reason for having it in the first place.

Still, none of this helps you find a list of all registered addresses for a domain owner. I might suggest that you ask the "LiveJournal Genie" for suggestions on that one. It's an open LiveJournal where people can ask questions on any topic, and anyone that reads can answer. The only stipulations for getting help are:

1. You have to begin the posted question with the phrase "Dear LJ Genie", and

2. You have to agree to thank anyone and everyone that posts with valid attempts at assistance.

The LiveJournal address is ljgenie.