domaintools.com

DomainTools offers many domain name research resources, including comprehensive Whois Lookup, Reverse Whois Lookup and Whois History. Some of the things you can do are find all domains owned by one owner, view the ownership history of a domain or see what a website looked like in the past. You will also find there many domain name monitoring tools and various buyer/seller tools.

Website: www.domaintools.com