Nice concept and good implementation. My only suggestion is get rid of the ads. Paid lists will be a huge revenue generator, no need to scare people off with ads.

I'd suggest checking out Google Hot Trends (http://www.google.com/trends/hottrends) and finding available domain names against that.

I had a site like this years ago and it did quite well. Looks like you found the right business model as well, domain squatters pay big money for these lists.

The only reason I stopped doing it was because I felt uneasy contributing to the domain name squatting problem.