Facebook tops our list again, with a valuation of $25 billion, up radically from $6.5 billion last year. Facebook continues to grow at a tremendous clip and now has more than 500 million users worldwide. The company will generate revenue of over $1 billion in 2010 and become cash flow positive.
Rounding out the top five: Zynga, the social game developer; Wikipedia, the free encyclopedia we think could be worth $5 billion if it tried to make money; Skype, which might go for $5 billion in an open market; and Craigslist, the wildly popular listings site that could coin money if it ever decided to do so.
#18 – Adknowledge
Estimated Value: $900 million
Business: Ad Network
Location: Kansas City, MO
CEO: Scott Lynn
Investors: Technology Crossover Ventures
