If you like this story, you can hit a share button at the bottom of this page to email it to a friend. You can tweet it or post it on Facebook—or Digg it, buzz it or tag it on Mister-Wong.com.

Wait, you ask, what’s Mister Wong? Unless you are one of the 297,000 users who visited this site in February, you probably haven’t heard of the European social bookmarking service—or for that matter, many of the 49 other sharing sites listed with names like Oknotizie, Kirtsy, and Meneame.

Welcome to the long tail of web sharing. Sure, Facebook has north of 400 million users, and it’s edging out email as the way people are most likely to pass links to their friends. Twitter is also a significant channel we use to distribute the news we care about. But the Web is made up of millions of passionate communities, and not all of them live atop these two platforms.

For a couple of enterprising startups intent on optimizing the traffic that comes from sharing, that’s an opportunity. Fittingly, theses services are called “AddThis” and “ShareThis.” Both provide customizable share buttons that publishers embed on their sites for free. AddThis, which is owned by widget network Clearspring Technologies, offers 271 sharing services to its publishers; ShareThis counts 50 sharing services in its portfolio. Each relies on algorithms to determine which buttons matter most to a user. If you happen to be a Mister-Wong.com aficionado, that button will pop up among your top choices as you read this story.

The companies’ founders argue that offering users more options for how to share their content can create a real traffic boost for some sites. Recently when social networking site Friendster added the “AddThis” button to its page, for example, traffic spiked 158% as Friendster users shared the content across other niche social networks. Even when that boost is smaller, web publishers are loathe to pass up a click or two when its free to download the tool.

The benefit for these startups is data—mountains of information about what content people choose to share, where they share it, and which sharing services are most likely to lead to clicks. Check out the services directory on AddThis, for example, and you can see that in the last 30 days, the rate at which people are sharing content on blogging platform Tumblr has jumped 276%. Or you can see a higher percentage of surfers tweet content in the United Kingdom than the United States. As people increasingly turn to Twitter streams, Facebook newsfeeds and other social services to navigate the web, this is crucial information for companies. Once, they aspired to rank high in a Google (GOOG) search; now they also want real estate on Facebook’s newsfeed.

However, this explosion of share buttons may not last forever. Over time, publishers will have to make a calculation about whether the extra attention they get from all the sharing options is worth sacrificing the data about where readers are posting content. Web behavior is consolidating, after all. Taken together, Facebook and Google (including YouTube, Gmail, and Google Images) accounted for more than 18% of Internet activity for the most recent week available according to Hitwise, or nearly one web visit in every five. The largest websites are growing larger and the long tail — all the publishers writing to audiences of a few readers — is growing longer. AddThis reports stories tagged on Mister-Wong have fallen five percent in the last 30 days.

Nevertheless, if you’re a Mister Wong fan, I’d encourage you to share this story using the bookmark at the bottom of this page. For now, you’ll find one.