1997 many people used email but couldn't even grasp the huge potential that lay ahead for email usuage. Same for google in 2000. Facebook's potential is staggering. They will easily gain 30% of the social networking market share.
Quote from dividend:
The most valuable asset they have is all the data mined and behavioral patterns of its users. The company itself is worth practically zero. And there is zero barrier to entry. Basically, it is the ultimate social honeypot. If I were an investor in these types of companies I would want to know what kind of information they log. The more they log and pierce user's privacies, the higher I would value these types of firms.
Quote from jamiereed123:
These chat/get together sites never sustain their movement.. After 4-5 years something new will be invented and facebook will be forgotten about- thing about it with music downloads and chat rooms.. ICQ, MIRC, Napster, etc all got outdated eventually when newer products were invented.

Quote from Daxtrader:
I will short every share available of facebook. I'll average down until I have nothing left. Facebook is nothing special at all. Anyone with decent comp sci skills could create another facebook. Google on the other hand has an actual business. So does yahoo. You are crazy to compare facebook to the sites you mentioned.