In my opinion you either need a few really dedicated guys (Lead Programmer, Interface Artist, Sprite Artist, Webmaster, Marketer) who believe in the site and willing to work very long hours at the start OR you need £180million (like the guy who set up king.com), so you can hire a team of people to work for you. Either way I feel that most new sites now will need to have a fairly strong unique selling point to give people a reason to move away from excellent sites like king.com