You have missed out the Stumbleupon because it's my favorite. Once your story got some exposure in it then you will receive the endless traffic.
I Like Socialiife its the only real-time marketing tool out there http://www.youtube.com/watch?v=mDhddxzFOk8
My fav. one is twitter. Most interesting feature of twitter is you have to explain (yourself/business/products etc.) in just 140 characters.