Most of the social media conversation tends to focus on Facebook and Twitter, but LinkedIn, the career-focused social network, may turn out to be the first of the bunch with a real business plan.

LinkedIn has been quietly building momentum, and it reached 45 million users this week, according to a tweet from LinkedIn's marketing project manager Florina Xhabija. The social network also had 16 million worldwide unique visitors and 331 million page views in June, according to TechCrunch, citing comScore data. That's more than double its June 2008 traffic, which saw 7.7 million unique visitors and 114 million page views.

Those numbers are nothing compared to the hundreds of millions of registered users on Facebook, but they represent terrific growth for a niche social network. And unlike other social networks, LinkedIn actually makes a profit ever year, which has led to rumors of a public offering.

While there's no news on that front, LinkedIn founder Reid Hoffman told iMedia in April that, "We've always believed that there would be an IPO in our future, and since we are profitable, we can do that when it feels right."