Facebook acquired Friend.ly, a social Q&A start-up based in Mountain View, Calif., for an undisclosed sum.

We're excited to announce that we recently acquired Friend.ly, a Silicon Valley start-up that created a really compelling way for people to express themselves and meet others through answering questions, said a Facebook spokesperson. We've admired the team's efforts for some time now, and we're looking forward to having Ed [Baker] and his colleagues make a big impact on the way millions of people connect and engage with each other on Facebook.

Friend.ly will continue to operate its own site, but its staff will join the Facebook team to develop new products for the social network.

We're excited about this because we feel the spirit of friend.ly aligns well with Facebook's vision, and we're thrilled to be joining such an innovative company, wrote the company in a blog post.

Until recently, Friend.ly was a Facebook Connect app that pulled data from Facebook profiles, like friend and Like lists, to ask more relevant questions. For example, if you like skiing, Friend.ly would ask questions like, Where's your favorite place to ski? This led to more engagement and more sharing.

Friend.ly experienced an enormous spike in traffic from its integration with Facebook, which might explain why the social network was so interested in buying the two-year Q&A start-up.  

Facebook  has a history of acquiring companies not based on products, but on the basis of talent and design prowess. Earlier this year, the social networking giant acquired the team behind a start-up called Sofa, a software firm based in Amsterdam that has developed icons for Firefox, TomTom, Nike and more.

We were just blown away by the Sofa team's work, from their Mac and Web software to the interfaces and brand identities they created for clients, said Kate Aronowitz, Facebook's director of design.

Similar to the Friend.ly acquisition, Facebook also let the Sofa staff relocate to Facebook's headquarters in Palo Alto, Calif., to join the Facebook team.

We expected to keep working at Sofa forever, the company said in a blog post announcing the talent acquisition. But after Facebook first made contact, we were quickly convinced to join forces.

In almost eight years of operation, Facebook has acquired 19 various start-ups and companies, including mobile app developer Snaptu, group messaging start-up Beluga, and the Winklevoss twins' start-up ConnectU. Several key Facebook faculty were brought over as results of an acquisition, including CTO Bret Taylor, who joined the team after Facebook bought social networking aggregator FriendFeed in  2009.

Facebook still plans to roll out Timeline profiles and Open Graph functionality to its 800 million users over the next few weeks.