Domain Investigation

Some online domain-related tools:
http://www.geektools.com/whois.php (whois)
http://xwhois.com (whois)
http://www.geektools.com/digtool.php (dig)
http://www.apnic.org/search/index.html (arin whois)
http://www.samspade.org/t (miscellaneous)
http://network-tools.com/ (miscellaneous)