social network and is now the &lt;a href="http://www.huffingtonpost.com/2012\\... target="_hplink"&gt;third most popular social network&lt;/a&gt; in America, trailing only Facebook and Twitter. &lt;br&gt; &lt;br&gt; You can &lt;a href="http://pinterest.com/" target="_hplink"&gt;request an invitation to join Pinterest here&lt;/a&gt;. Tagged Tagged has a remarkably similar arc to Facebook: Also founded in 2004, and also originally tageted at young people, Tagged is now open to everyone and allows you to customize your profile, play games, message friends, post photos, and meet new people. It has more than 300 million users and more than twenty million monthly active users -- not too shabby, and perhaps worth a look if you want a robust Facebook alternative that's not going anywhere. To see what Tagged is all about, check out this video introduction for beginners. You can &lt;a href="http://www.tagged.com/?" target="_hplink"&gt;sign up for Tagged here&lt;/a&gt;. Path Path is one of several new social networks that seeks to improve on Facebook by making the experience more private and personal: Users are limited to 150 friends on the mobile-only service. A user is instructed to only add his or her closest friends, or anyone you'd invite to your birthday party; the average Path user &lt;a href="http://www.nytimes.com/2012/04/15/\\... target="_hplink"&gt;has 40 connections&lt;/a&gt;. Path is sort of like a daily online journal that you open to your friends: You can post photos and videos using your smartphone's camera, update your location, share what songs you're listening to and more. Path has been praised for its intimate feeling and clean design. For more on this social network and