Since I now work on ads I wanted to get some experience with using them. I've now added an ad to the bottom of each post here, below the comments. I used DoubleClick Small Business to set up simple images like:

This lets me experience the world both as an advertiser (making the ad) and a publisher (having a page that can show an ad). It's like the me who runs trycontra.com made a direct deal with the me who runs jefftk.com to buy some ad space.

Another part of the advertising world is a networks. Instead of making direct deals with advertisers I can use an ad network as a middleman who makes my ad space available to anyone who wants to pay. The main downside of this is I don't like these ads as much as the ones I made myself, so I've set up this ad slot to only accept bids of at least $5 per thousand page views ($5 CPM):

This is a pretty high bar, especially for a slot all the way at the bottom of the page. Over the last two days advertisers have only been willing to bid that much 3% of the time:

Note that the "Revenue" it's reporting for the price priority ads isn't real revenue, since it doesn't know I'm just using $5 as a threshold and no money is changing hands.

Overall this seems good, and irresponsibly extrapolating from two days of data I'm on track to make about $9/year. To see this ad live, scroll down to the very bottom of the page. Find out whether you're one of the lucky 3% whose ad views are valuable enough to be worth $5 per thousand!