Picture 16RockYou , one of the largest developers and ad networks built around Facebook’s platform, just raised $50 million in venture funding from Softbank. That brings RockYou’s total funding to $119 million from investors including Sequoia Capital, Lightspeed Venture Partners, Partech International and DCM. Softbank was the only participant in this round, the company says.

Venture capital firms have got to be a bit emboldened about companies built around Facebook’s platform given last week’s sale of Playfish to Electronic Arts for as much as $400 million. RockYou is a bit different — it operates a distributed ad network across Facebook, MySpace, Bebo, Orkut, Hi5 and Friendster. The company is also pushing into virtual goods with a new gifts app on MySpace.

From what RockYou’s vice president of sales Lisa Marino tells us, it looks like the company will be expanding its footprint in game advertising and in its overseas operations. RockYou is on track to bring in between $30 and 40 million in revenue this year and is aiming to be profitable by the third quarter of next year, she said. The company has about 1,000 applications on its ad network and 213 million monthly users.

“Softbank was looking for us to be a little more aggressive in our application releases, especially in the Asian market,” Marino said. “They wanted us to fundamentally grow more quickly, and so that was the impetus for this deal.”

RockYou’s main rival is Slide. On Facebook, Rockyou has the upper hand in numbers of users, with 40.5 million monthly active users, compared to 27 million for Slide, according to AppData. With those numbers, RockYou is the third-largest developer on Facebook, behind only Zynga and Playfish.

RockYou was founded in 2005 by Lance Tokuda and Jia Shen. The two men worked together on a slide show project at software developer Iconix, and their first product at RockYou was also a slide show service. That resulted in a lawsuit that was eventually settled. RockYou’s apps include Super Wall, Hug Me, Likeness, Vampires, Birthdays, Slideshows, MyGifts and others.