I read somewhere that the single most important predictor of an individual's obesity risk is whether or not their friends are obese. Eventually we can count on Facebook's implementation of machine vision, weight estimating algorithms, and the publicness policies to justify them. That will be super awesome because it will save us all the trouble of updating our weight on our profile manually. We won't even have to own tweeting scales to know just how obese are friends are.
In such a perfectly data rich world, Facebook's voracious crew of ever curiouser Wants will be able to use the edge-strength-weighted average mass of your friends to easily predict your future displacement too. Where your friends are you will stochastically follow.
Just imagine your sense of wonder when you are innocently reading a well-paid blogger on Huffington Post and bam! An ad for a globo gym pops up in the margin. Why will that instill "a sense of wonder" you ask? Because you are two screening and 30 seconds later an ad for the exact same globo gym appears on your television too. Whoa! And the crazy thing is just this morning you were standing in front of the mirror thinking "Dammit, I wish Tim Ferris wasn't such a tool, because I'm almost as fat as my buddy Dave and I really need to do something about it, but I can't read that 4 Hour Fitness horseshit."