register.com's whois lookup is still the one I use.

It's at this spot. A whois lookup for a domain name should give you some data about who owns the domain name and, in a pinch, I've used this to find a way to get ahold of someone at a web site by way of phone number or email address. The domain name will point at nameservers and the primary nameserver (the others are failovers for the first) will route traffic based on DNS records. The gunk that comes back from register.com for register.com itself is:

Domain Name: register.com
Registry Domain ID: 3441369_DOMAIN_COM-VRSN
Registrar WHOIS Server: whois.register.com
Registrar URL: http://www.register.com
Updated Date: 2009-08-26T04:00:00Z
Creation Date: 1994-11-01T05:00:00Z
Registrar Registration Expiration Date: 2019-08-04T04:00:00Z
Registrar: Register.com, Inc.
Registrar IANA ID: 9
Registrar Abuse Contact Email: abuse@web.com
Registrar Abuse Contact Phone: +1.8773812449
Reseller:
Domain Status: clientTransferProhibited http://icann.org/epp#clientTransferProhibited
Domain Status: clientUpdateProhibited http://icann.org/epp#clientUpdateProhibited
Domain Status: clientRenewProhibited http://icann.org/epp#clientRenewProhibited
Domain Status: clientDeleteProhibited http://icann.org/epp#clientDeleteProhibited
Registry Registrant ID:
Registrant Name: Domain Registrar
Registrant Organization: Register.Com, Inc.
Registrant Street: 575 8th Avenue
Registrant City: New York
Registrant State/Province: NY
Registrant Postal Code: 10018
Registrant Country: US
Registrant Phone: +1.9027492701
Registrant Phone Ext.:
Registrant Fax:
Registrant Fax Ext.:
Registrant Email: domainregistrar@register.com
Registry Admin ID:
Admin Name: Domain Registrar
Admin Organization: Register.Com, Inc.
Admin Street: 575 8th Avenue
Admin City: New York
Admin State/Province: NY
Admin Postal Code: 10018
Admin Country: US
Admin Phone: +1.9027492701
Admin Phone Ext.:
Admin Fax:
Admin Fax Ext.:
Admin Email: domainregistrar@register.com
Registry Tech ID:
Tech Name: Domain Registrar
Tech Organization: Register.Com, Inc.
Tech Street: 575 8th Avenue
Tech City: New York
Tech State/Province: NY
Tech Postal Code: 10018
Tech Country: US
Tech Phone: +1.9027492701
Tech Phone Ext.:
Tech Fax:
Tech Fax Ext.:
Tech Email: domainregistrar@register.com
Name Server: ns2.register.com
Name Server: ns3.register.com
Name Server: ns4.register.com
Name Server: ns1.register.com
DNSSEC: Unsigned
URL of the ICANN WHOIS Data Problem Reporting System: http://wdprs.internic.net/
>>> Last update of WHOIS database: 2009-08-26T04:00:00Z <<<