Media companies aren’t the only ones looking to take advantage of the popularity of social networking sites. Online retailer Amazon.com (AMZN) is throwing its hat into the ring as well with a question and answer site called Askville.

Last December, Amazon quietly launched a beta version of Askville. But this week, Amazon e-mailed several of its customers with news about this site. I received the following e-mail Thursday morning.

You’re Invited!

As a valued Amazon customer, you’ve been specially picked to get an early look at a new website Amazon has just launched called Askville. Askville is a place where you can ask any question on any topic and get real answers from real people. It’s a fun place to meet others with similar interests to you and a place where you can share what you know. You can learn something new every day or help and meet others using your knowledge. It’s new, and best of all, it’s free!

At first blush, the site seems pretty similar to Yahoo!’s (YHOO) Yahoo Answers, Answers.com (ANSW) and privately held wis.dm. Upon closer inspection, there are some notable differences.

For one, Amazon lets people rate other’s answers with something called experience points. Users vote on how valuable an answer to a certain question is and based on the results, people can gain or lose experience points. In addition, these experience points, as well as other activities such as simply asking a question, voting on a question or even logging on to the site, help users acquire something Amazon calls Quest Coins.

Now what, you may ask, are Quest Coins? Amazon describes them as virtual currency that can be used on a yet-to-be launched site called Questville. Amazon boasts in its FAQ section for Questville that “on Questville you will be able to use your Quest Coins to participate in exciting new adventures and other cool things!”

It all sounds very mysterious. And a spokesman for Amazon told me in an e-mail that the company was not willing to discuss the business strategy for Askville or Questville at this time. The notion of being rewarded for user participation is interesting though. But what will the rewards actually be? It will probably depend on what exactly Questville is.

Will Questville be the latest entry in the rapidly growing virtual world market? If so, Quest Coins could be Amazon’s answer to Second Life’s Linden Dollars or There.com’s ThereBucks.

Perhaps more intriguing would be the possibility that Quest Coins could be redeemed not for virtual bling for your avatar but for real purchases on Amazon.com. Maybe 500 Quest Coins will wind up being equivalent to say, $10 off a purchase of “Harry Potter and the Deathly Hallows” or the Season 1 DVD set of “Heroes.”

If that’s the case, Askville and Questville could help stimulate more sales at Amazon.com. And of course, if Askville and Questville also become popular enough so that they can sell online advertising then that’s potentially an even bigger windfall.

Alex Blum, CEO of KickApps, a privately held firm that develops tools to help companies incorporate user-generated content and other social networking features on their Web sites, said he expects more companies outside the media realm to try and cash in on the social networking trend since social networking can be an effective way for marketers to target specific customers. To that end, some of his customers are Procter & Gamble (PG) and Kraft (KFT).

“Any niche community that forms around a passion or brand should be able to have a social networking site as robust as MySpace, YouTube or Flickr,” he said, referring to the popular user-generated sites owned by News Corp. (NWS), Google (GOOG) and Yahoo respectively.

But it remains to be seen if Amazon will be able to become a hit in social networking or not. After all, other efforts to branch out beyond retailing haven’t exactly fared well. Most notably, Amazon’s ballyhooed A9 search engine failed to live up to the considerable hype.