LinkedIn just announced its fourth quarter and full 2012 financial results, reporting an astounding $303.6 million in revenue for the fourth quarter (an increase of 81% compared to $167.7 million the previous year). LinkedIn continues to grow at a rate of two new members per second, with 15 million accounts added in Q4 and approximately 202 million members total as of January 1.

So what are the reasons behind LinkedIn’s success? Innovation. Several large-scale features were rolled out during the latter half of 2012, including redesigned LinkedIn Company Pages, how-you’re-connected graphs, Influencers, endorsements, new follow capabilities (without having to officially connect) and blogging features to generate original content.

“2012 was a transformative year for LinkedIn,” said Jeff Weiner, LinkedIn CEO. “We exited 2011 having successfully revamped our underlying development infrastructure. Based on that investment, we said that 2012 would be a year of accelerated product innovation, and it was. The products we delivered throughout the year drove member engagement and financial results to record levels in the fourth quarter.” LinkedIn CFO Steve Sordello added, “Continued investment in our talent and technology infrastructure drove momentum in both product and monetization, resulting in record revenue, profitability, and cash flow. As we look forward to 2013, we remain excited about the value LinkedIn will create for members and customers in the coming year.”

What’s one feature you’d like LinkedIn to add or develop in 2013?