I've written about the power of the social media sites (Water Balloon Stunt + Digg Homepage = 33,000 visits in 24 hours).
In a similar (but smaller and unplanned) example, my interview with Bill got picked up by Stumbleupon (thanks, sevenblock!) most likely due to the MIT poker angle. (The bulk of the interview was about ECOA, email change of address -- important, but much much less cool than bringing down the house in Vegas.)
That post, which had been seeing about 15 readers per day, today spiked in traffic seven-fold, up to 118 visits, due to that single Stumbleupon.
Here's the Feedburner graph: