Use social networks to boost traffic to your site

If you don't want to base only on organic traffic (from search engines), you must be active on your social networks.
You can use for example such networks like:

• Facebook
• Twitter
• Google+
• LinkedIn
• Pinterest

Besides, if you are a blogger, you can be active also on some others networks dedicated for bloggers:

• bloggers.com
• www.networkedblogs.com

And what are your favorite social or bloger's networks?