Made me wonder what registrar major internet companies use. Fortunately, whois can tell us:
facebook.com -> markmonitor
google.com -> markmonitor
amazon.com -> markmonitor
youtube.com -> markmonitor
yahoo.com -> markmonitor
baidu.com -> markmonitor
wikipedia.org -> markmonitor
linkedin.com -> markmonitor
ebay.com -> markmonitor
bing.com -> markmonitor
microsoft.com -> markmonitor
paypal.com -> markmonitor
flickr.com -> markmonitor
blogger.com -> markmonitor
wordpress.com -> markmonitor
live.com -> corporatedomains
twitter.com -> corporatedomains
apple.com -> corporatedomains
cnn.com -> corporatedomains
theguardian.com -> tucows
TinyURL.com -> tucows
theguardian.com -> tucows
huffingtonpost.com -> melbourneit
t.co -> melbourneit
bitly.com -> godaddy
barackobama.com -> godaddy
dell.com -> safenames
reddit.com -> gandi
imgur.com -> enom
ycombinator.com -> easydns
craigslist.org -> netsol
I don't know whether markmonitor deliberately try to get popular websites as clients, aiming for some sort of halo effect.