The world’s largest social network, Facebook, is planning a number of acquisitions that will improve site design and advance mobile features. The company is moving quickly to increase the amount of time users spend on its site, but the company is also eager to launch improvements in response to growing competition, specifically Google+.

Facebook is also hoping to make the site run smoother and more reliably. Since its userbase has grown to more than 750 million, Facebook needs to support its growth without adding to the site’s complexity. In total, the company has made 13 acquisitions so far this year and is expected to acquire as many as seven more by year’s end.

“Two years ago we didn’t have a track record in acquisitions,” said Vaughan Smith, Facebook’s director of corporate development. “While we expected them to work well, it was still a crapshoot how they’d turn out. We’ve built a culture that supports entrepreneurs, and it’s working incredibly well.”

As a closely held company, Facebook’s financials are a bit of a mystery. But according to Bloomberg, the social network has generated about $2 billion in earnings this year through advertising and commissions from the sale of virtual goods. Another $2 billion was raised from investors.

Although Facebook has plenty of cash, it’s nothing next Google. The search giant has $39.1 billion in cash, which could easily help fuel its new social networking service, Google+. According to ComScore, the service has already had attracted 29 million people by the end of July. Nevertheless, Facebook is eager to improve its service and acquire new talent in any way it can.

“Facebook is just trying to get the smartest people possible in any way it can,” said Debra Aho Williamson, an EMarketer Inc. analyst. “The idea of bringing in new talent, smart talent, people who have created interesting products that Facebook can capitalize on, is going to be important to them.”

With new acquisitions and fresh talent on board, expect tweaks to Facebook’s user-interface in the near future, as well as the launch of its long-awaited iPad app.