Social media offers companies a huge opportunity--the ability to analyze customers' conversations in real time. But what happens when you want to analyze conversations that happened six months or a year ago? Good luck finding that data--or wading through it, for that matter.

Gnip, a social data start-up founded in Boulder, Colorado in 2008, has been working on that very problem for a while. In fact, last year Twitter partnered with Gnip to help collect its complete six-year history of public tweets for the Library of Congress.

Starting Wednesday, Gnip is making that same trove of data available for companies to analyze--for a price, of course. The company calls this new product Historical PowerTrack for Twitter.

"To date, companies have only had the ability to do real-time analysis of social data," says Chris Moody, Gnip's COO. "This is the next natural evolution. What businesses really need is context."

So, for example, a company might announce a big product launch and use Gnip's data to analyze how the social media reaction to it compared with, say, what Twitter users said about a product launch done the year before. Financial services companies have been interested in applying their trading algorithms to historical Twitter data to test the platform's predictive abilities. Even cultural researchers are keen to analyze Twitter's stream of tweets, especially in light of social media's role in the Arab Spring movement. 

Gnip doesn't provide analysis or glean insights from the data; that part is up to businesses, including the third-party social media monitoring companies that represent a big chunk of Gnip's customers. 

"We aspire to be the source of record for social data," Moody says.

If the Twitter partnership is any indication, Gnip is well on its way. The start-up also collects (and licenses) some data from Facebook, Tumblr, Wordpress, Google+, and a host of other sources.