The forum hosted it and a new company sponsored it. The way that one in particular worked was people needed to sign up to the new company and get the most referrals and or revenue.
CheapAssGamer for black friday had pretty a pretty giant prize, something like a 360, PS3, Wii, 3DS, PS Vita, all came with games and $500 in amazon credit. The thing is this wasn't all payed out by the owner as for example the $500 credit was given as a promotion by an amazon rep.
Thanks Gimgak, that seems to be one of the tricks to running a successful contest, get sponsors to put up prizes. They get the publicity in return and your members get the benefit of better prizes.