Editor's Note - Although directory links have been reduced in importance within Google's algorithmic updates, some still have value. Specifically, the directories that are local, niche or highly cultivated (like http://www.hotsaucenetwork.com/, if you sell hot sauce, you would want to be in this directory). Because of the nature of niche directories we cannot list them here for you. However, what are still extremely powerful are Social Media Platforms...

The Top Social Media Sites

Social SiteJoinTypeComments
TwitterJoinSocial CommunicationShare and discover what’s happening right now, anywhere in the world.
FacebookJoinSocial NetworkingFacebook helps you connect and share with the people in your life.
LinkedInJoinSocial NetworkingOver 85 million professionals use LinkedIn to exchange information, ideas and opportunities
Google+JoinSocial NetworkingShare updates, photos, videos, and more. Start conversations about the things you find interesting.
DiggJoinSocial NewsStill a top social bookmarking site. Hitting the front page can bring massive server-crashing amounts of traffic.
StumbleUponJoinSocial NewsCan be a great source of ongoing traffic.
RedditJoinSocial NewsCommunity groups on many varied topics.
YouTubeJoinGoogle's Social Video SiteYouTube is extremely powerful with Millions of viewer every month! Your Google account is automatically tied to YouTube so it's just a matter of going to YouTube while logged into Google to access and personalize your channel. Here are details on setting up your channel like a pro.
PinterestJoinSocial Image BookmarkingNow the #5 social bookmarking site behind Facebook, YouTube, Twitter and Reddit. If you are in an image-rich industry, this is a must-use for everyday social marketing.
eBaum's WorldJoinSocial VideoHigh-traffic social bookmarking site perfect for link bait submission and blog post promotion.
Folkd.comJoinSocial BookmarkingA top global social bookmarking site that's been around since 2006. Links are nofollow but can lead to good traffic if you hit the front-page.
BuzzFeedJoinSocial NewsBreaking top traffic social news site. Provides an advertising option to drive traffic to highlighted blog posts or link bait pieces for initial viral buzz.
TumblrJoinSocial MicrobloggingOwned by Yahoo, as of September 1, 2015, Tumblr hosts over 252 million blogs. Provides advertising options and can be leveraged for great traffic.
InstagramFree AppSocial Image SharingA Image sharing platform growing in popularity, that allows you to upload, edit and share images to Facebook, Flickr and Twitter. You can also use it to checkin on Foursquare by picking a location for your image.
SnapchatFree AppSocial NetworkingSnapchat helps you connect and share with an audience.