Most important whois in the world. The whois that defines authoritatively which whois to ask for the rest of the info.
Also the place to report invalid or fraudelent whois data.
I have used this site and found the contents useful and informative.
Good free information on website registrations.
InterNIC—Public Information Regarding Internet Domain Name Registration Services
Public Information Regarding Internet Domain Name Registration Services
Not the best whois in the world… very limited info.