Just my two cents, I don't know how viable this business model is anymore, back in the day it was fairly easy to create a site and make it profitable almost instantly with adsense. Now it seems CPC has gone so much that 3x the traffic is required to make the same amount you would have just a few years ago.
Personally what I have done is to create a few sites and let them earn whatever they will earn with adsense while I work my day job. Obviously its not enough for me to quit my day job but having some extra each month is nice and when I have a good month its like a bonus.
One of my sites got absolutely killed by Panda, so I kind of threw my hands up and decided I wouldn't work on it anymore, so now I got very little traffic from google but my referrals from other sources have increased to the point where I actually have more traffic than I did pre-Panda.