During the next two years, you're going to hear a lot of people telling your to integrate all of your data sources.
It's 2000 all over again. Back then, experts demanded that you integrate online data with offline data, for a "360 degree view" of the customer. You followed suit, and you learned that it was important to integrate data to better understand your customer. You also learned that you didn't generate the unfettered profits promised by business leaders.
Over the next two years, there will be numerous products and services that allow you to append "social profiles" to your customer base. There will be a gold rush to describe how customers use social media, an attempt to make the information actionable.
In the short term, why not ask your customers, at checkout, if the customer is on Facebook, or if the customer is on Twitter? Just give the customer a couple of boxes to check. Then add that information to your customer database. Analyze customer behavior by these simple indicators.
If you're a classic cataloger, you may find that you can reduce annual contacts by a couple, just by knowing this information.