If you want to rotate ads in your blog, WPAds Plugin can help you.
Simply create a banner (using code of your ad). It can be any kind of ad including image, banner or text ads. Attach the banner to the zone. After that just place the WPAds line of code in the theme or Post. To rotate, attach multiple banners to the zone. You can also assign a weight to the banner. The only limitation of the plugin is that there is no easy way of adding the ads to the sidebar as the Plugin does not come with sidebar widget.
