For the past two years I have been conducting some extensive testing with a number of my clients in various fields - software, consulting services, academics, non-profits, entertainment, and self improvement - and here's what I came up with at the end of the study. I'm interested in one metric - conversion to sales.
Conversion to Sales
Website: 29.5% of sales
Facebook: 4% of sales
Twitter: 1.5% of sales
Print: 2% of sales
Book: 9% of sales
E-book: 7% of sales
Email newsletter and blog combined: 42% of sales
The old rules of online marketing beat social media by a mile, period.
See you later, FB and Twitter...