I just got this demo from a social media marketing company. With a list of 100,000 email addresses they've figured all kinds of crap out about people based on demographics, political worldview, religion, consumption habits, etc. as well as the usual demographics.
You can get a report on an individual email address that tells you everything the person has ever fanned, liked, shared, etc., how many friends/connection she has, how active she is and on which sites, what her favorite music is, etc. etc. It then correlates all that with demographics to pull out a particular group of email addresses that hearts Obama, hates Ayn Rand, works in IT, etc.
It will even correlate email addresses so that if you have a web-based email account you use, as well as one from an ISP (e.g. @cox.net, @aol.com, @verizon), to indicate that the email address you are trying to get data on is likely also the same person connected to another email address.
baking our own bread and circuses indeed!