15. Airbnb is valued around $2.5 billion.

Airbnb closed a $200 million round of financing in 2012, bringing its total funding to $526 million.

Airbnb was previously valued at $2.5 billion; it first joined the $1 billion valuation club when it raised $112 million in 2011.

The latest rumor is that Airbnb is raising another round at a whopping $10 billion valuation, which would value it more than Hyatt hotels.