alt Hacker NewsThey specialize in domains management for businesses who consider their domain to be _very_ important. Think Google, Amazon, Microsoft, Wikipedia... (all of those are listed as clients on the wiki page)
As in "pay a lot of money", and we'll dedicate someone to your domain who makes sure that "giving a domain to a stranger without any documents" will _never_ happen.
a number of the largest companies that used to be 'clients' of markmonitor have now basically become their own domain registrars and have a direct relationship with ICANN. Amazon for instance. It's curious that google was one and has offloaded it to squarespace.