An ongoing comparison of Domain Name Registrars, more like Registrar Watch shows that GoDaddy alone has 36 Million Domain names registered, combined with WildWestDomains has more than 40 million, While the next in the list ENOM has 9.5 million, So the GoDaddy group is by far the largest registrar for domain names, 4 times the size of the second in the list !
From that website, it seems GoDaddy is the largest Shared Hosting provider as well, but i can not be sure about Servers, as i doubt they come close to theplanet (Which now owns EV1SERVERS)
I wonder how the new ICANN plans to introduce TLDs will affect the map of the domain name business, i am currently investigating the ICANN new ideas as they have a meeting very soon concerning the issue.
Also worth mentioning is that this is the first time i get to see the actual cost to registrars, the website lists the registry costs (For example how much verisign charges for .com and .net) and how much Public Interest Registry charges for a .ORG, so check it out