taberstruths - 6:56 pm on Apr 26, 2013 (gmt 0)
SU is good for testing but I haven't found it very good as a real traffic source. FB is the best source for my niche for real traffic and viral exposure. Pinterest of all things sends me a steady stream of traffic as well. Works well for my niche and because all of my articles have at least 1 picture.
The reason that FB, SU, Pinterest ect. have been successful is not because of Google but because they found something that users like to do and so users interact with their site and tell their friends about it.