Here's a quick method of finding possible buyers for your domain name,
1. Go to WHOIS.SC and find owners of variations of your domain name. If you own example.com, there's a chance the owners of example123.com, exam-ple.com or example.us might be interested. The key is finding companies that can benefit from aquiring your name, so try to seek out the owners of "similar, but worse" domains.
2. Go to Google.com and search for the keywords contained in your domain. Make a list of all the paying advertisers that appear in the "Sponsored Links".
3. Go to Overture.com and search for the keywords contained in your domain. Make a list of all the paying advertisers. (Click "View Advertisers' Max Bids")
These three steps will usually produce a decent sized list of potential buyers for your name. From there you can contact the companies individually and see if there's any interest in aquiring your name.
PLEASE DO NOT SPAM! Mass mailing all these companies with a single spam email is a bad idea! Any time you are trying to sell your domain you should be contacting these companies indivudually with a personal email, a letter by snail mail or a simple phone call. Figure out how these companies can benefit by owning your domain and approach them with this information. Other threads on NP contain advice about how to go about this.
Don't get your hopes up too high when searching out end users. You might contact 30 companies and not receive any interest. Don't fret, just move on to the next domain.
(^^ this advice I posted in
another thread a few months ago -- check it out for other good pointers from NP'rs)