Full disclosure: I'm doing this as a trial to test some web analytics software. We offer interactive, media and analytics capabilities at my office, and I find I'm frequently in position to communicate these offerings to clients. My previous agency roles didn't have this expertise, and the best way to learn about them was to implement them myself. I'm learning as I go...trialing the Google AdSense program, and soon will have some ads featured from BlogHer.
Not a red cent has been made, and frankly, I'm fine if I don't make anything - it's more of a tool to figure out what can be done in the online space.
Happy browsing...