In 2002, Eric Schmidt invited me to spend a year at Google.  I asked him what I should work on and he said "why don't you take a look at this ad auction --- I think it might make us a little money."  
I followed his suggestion and created a model of the Google Ad Auction.  This talk will be a bit about the history of that work, but mostly about how we used the auction model for subsequent decisions over the next few years.
The intent is to convey how the theory influenced the practice in this particular domain.