From Hoster Talk:
WHOIS Tools is a free WHOIS and DNS lookup application, designed to help users to look up the WHOIS records and DNS information of a Web site. The application is particularly useful to Web designers and developers for looking up Whois and DNS information for the domain or IP address of their choice, checking the correctness of domain binding to a host, checking mail settings and searching for the contact information of a Web site owner.
Using WHOIS Tools is absolutely simple. Just open the application and type in the keyword into the field and see what comes up. The application allows you to find out the domain registrar, geographic location of the server by a Web site address, geographic location by IP address, IP address of a Web site, hostname from an IP address, DNS servers for a Web site, mail MX records for a Web site and hostmaster`s e-mail. WHOIS Tools contacts many online databases to find the information you need and if it finds anything relevant, you can see it on the screen.