3 Emerging Social Networks to Keep an Eye On These new tools should be on your radar. Here's why.

When it comes to social media, your head is likely buried in projects involving established social networks such as Facebook and Twitter. Sometimes you need to take a breath and see what else is out there -- to forecast the popular social networks of tomorrow.

We're not talking Instagram or Tumblr; you know about those sites. We're also not suggesting Facebook is going to evaporate. It's not going anywhere for now.

But, for one reason or another, the following three sites are, at the very least, worth knowing.

1. Medium
Quite simply, Medium is a blogging site, though its founders describe it as an extension of Twitter. "A place where you can find and share knowledge, ideas, and stories -- specifically, ones that need more than 140 characters and are not just for your friends," the site promises.

The About Us page of Medium is packed with lofty language stressing that the site favors quality over quantity -- a noble pursuit in the Internet age.

Here's how it works: You write a blog, which appears in one of the site's many "collections" -- such as "Advice to New Graduates" or "Airport Stories" -- or on the site's homepage. Users vote (or "recommend") posts. How prominently a post is displayed on the site depends on how many votes it receives.

The design of Medium is clean and sharp, a real pleasure to the eye.

Anyone with a Twitter account can log in and start reading and voting, but you'll need an invite from the folks at Medium to actually write something. It plans to open up the site in the future.

Why you should care: Medium was created by Evan Williams and Biz Stone, whom you may recognize as the guys who started Twitter and Blogger. With that kind of track record, you would assume the site will take off.

2. Whisper
This is an iPhone app that promises anonymity. With Whisper, users post secrets, known as whispers, which appear in the form of an online postcard. These posts are anonymous. Other users can then respond with their whispers, send messages, or simply leave a heart on the post.

According to Business Insider, more than 1 million people have uploaded roughly 8 million whispers.

Why you should care: Last week, the app received $3 million in funding. It's also gaining steam among college students -- the ones who will soon be invading your offices. Tech blogs such as TechCrunch are calling it the next big thing.

3. Sina Weibo
Billed as China's Twitter, Sina Weibo has twice the users as Twitter.

Brands such as Pizza Hut have embraced the site, as have celebrities, including some Western celebs like Tom Cruise, who has more than 4.2 million followers on Sina Weibo. There's even a U.S.version of Weibo, though that's mostly indecipherable (unless you understand Mandarin Chinese). There is at least one service, called Transfluencer, helping American brands post to Weibo.

Why you should care: According to Mashable, 22 percent of China's population of more than 1.3 billion people are signed up for Sina Weibo. According to our calculations that's, well, a lot of people.