There is a new WordPress plugin called Max Banner Ads that enables affiliates to add and rotate banners in blogs without editing themes or monkeying with the codes.
I have been a user of OpenX to serve ads for quite some time, and I’m very happy with the OpenX hosted solution. But I’d say there are more bells and whistles than needed with OpenX for the average affiliate.
If you’re simply looking for a means to easily insert and rotate ads, as well as tracking impressions and clicks, Max Banner Ads looks like an ideal solution.