Hear that? That's the sound of a celebrity augmenting his or her income at the rate of 140 characters or less.

If you have a Twitter account, and you choose to follow one or more A-list celebrities, you may have noticed that sometimes they tweet about how much they enjoy a certain product or service.Now, you didn't think they did that just because they enjoyed that product or service, did you? No, they are probably being paid to put a tweet out (which, by the bye, they don't even write). And some of them get paid quite well.

There are several companies whose sole reason for being is to connect celebs with advertising partners. The pay rate depends on the number of followers a celebrity has, as well as how many re-tweets and shares the message gets. The largest company in the tweet-for-pay business is Ad.ly, whose celeb list includes Kim Kardasian, Snoop Dogg, and Charlie Sheen.

According to an article in the new issue of New York magazine [on newsstands today]Snoop Dogg pulls down around $8,000 for a sponsored tweet [which, at least as of now, don't have to be identified as paid advertising], while "Kim K" gets paid a cool ten-grand for her paid posts.

But one celeb, at least for a while, put all the other stars in the dust: at the height of his "Winning" rampage across America, Charlie Sheen was getting an amazing fifty-thousand dollars per tweet. And he was reputedly more than worth it. One advertisers said that Sheen's promotion of their service got them one million visits to their website!

Is it ethical? Well, probably not. Is it going to stop any time soon? Again, probably not...

(HuffingtonPost.com) {Further information from Vulture.com}