Airbnb
The round was first announced in October, when Airbnb CTO Nate Blecharczyk confirmed it was in the works and that Founders Fund was an investor.
Airbnb, which lets people rent out their homes to others while they're away, was previously valued at ~ $2.5 billion. Investors include Y Combinator, Sequoia Capital, Greylock Partners, SV Angel, Ashton Kutcher, Andreessen Horowitz, General Catalyst Partners, Jeff Bezos and Digital Sky Technologies.
As of 2012, 15 million nights had been booked on Airbnb.