ARIN
APNIC
Canadian domain registration
CIRA
.com .org .net
Website and email forwarding.
DNS StuffSeveral 'whois' servers; RDNS lookup; ping tests; CIDR / Netmask lookup; decimal IP translations; traceroute; spam database; more
US .gov
Looking to buy or sell a domain name?
Internet Corporation for Assigned Names and Numbers
European registration services.
Swiss registration for CH and LI domains