Here is a great little infographic from MGD Advertising talking about ROI, and Social Media. One interesting fact that I saw was an 80% increase in the use of Social Media to recruit new talent. I was also surprised that MySpace is still being included in the stats.
If you were wondering whether or not your Social Media marketing strategy was going to pay off, this might shed some light on your investment.
Modular 4 
Interesting statistics. I think the one about only 11% of companies using social media in their marketing have been doing so for more than 3 years is fascinating- shows how quick and recent the uptake has been!