Drax, a rotator can be made very simple. I did it 12 years ago with JavaScript. All client side and no system resources on my end. Back in those days even the smallest logo on thehun would kill any server. So I came up with a client side solution. Might be something to look in to. Especially now with OpenX there are very nice options. On
http://search.thehun.net we use lazy loading ads. Those are great, they only load a banner once it is visible on the screen. Very good use of system resources, nothing is wasted