When I started a Facebook account a year ago, something occurred to me that I am sure others have recognized. As my group of Facebook friends grew (670 today), I started to view the group as an asset. This was my group and while smaller, it resembled the lists publishing companies routinely rent out to direct mailers. The difference is I owned the Facebook group. For the purposes of this post, I’ll call it my personal audience.

I have used Facebook to promote content for my previous magazine’s web site, but felt like I could use that personal audience to more directly benefit me. After all, these 670 people were mostly colleagues and contacts I had built up over the 30+ year journalism career. Mine is an influential group of very active journalists and marketers. Without Facebook and my diligence in tracking down these folks, contact with them would have been lost.

To be honest, I have only started to experiment with posting real content on Twitter and Facebook. While the allure is more possibility than reality, social networks can drive web traffic. And now as a freelancer, my interest in social networks like Facebook and Twitter is on steroids.  I want to learn how to build, define and leverage these groups that Twitter and Facebook help you bring together — without spamming anyone, of course.

Others are doing it. I am hardly the first. A couple of times a week, I get Facebook invitations to check out someone’s blog or to join their cause or group. I am part of as many many personal audiences as I have friends on Facebook.

Twitter is another place to build a personal audiences. Some twits, tweetsters, tweeters – whatever us twitterers call ourselves- have followings that rival the size of newspaper and magazine circulations. Naturally, it helps to be famous: Barack Obama has 223,405 followers, but some people you may have never heard of have big personal audiences.

Tech journalist Leo Laporte has 81,044 followers. Tech maven Jason Calacanis has 55,292 and venture capitalist  Guy Kawasaki has 57,097. If these twits are following as many as are following them, a torrent of tweets must be coming at them. Check out the tweet counter. It’s running as fast as the U.S. National Debt Clock in New York.

Regardless, there’s power, branding and  and hopefully some money in those personal audiences. Strip out impoverished students and it’s a fairly safe to assume a pretty well-heeled and digitally literate demographic is buried within the vast twit ranks. I noticed Guy uses Adjix, which optionally embeds text ads in the shortened URLs commonly found in twitter tweets. Adjix promises revenue, but I have no idea about the potential. That the subject for another dozen posts.

I blogged Saturday about how Twitter has emerged as a news medium. Put two and two together and you can see how personal audiences can work like newspaper circulations. It’s all about reach and we all have it like never before.