The official mrdeleted.com Whois Lookup. Can search avalailability at various domain registrars if it is no whois is showing.
This will search the Whois on any domain with the click of the icon on top on the browser. It will also allow you to search a domain name at several different registrars if the name is available, so you can register it.
Now if you click a domain name and it shows as non existent, you can register it for yourself!