KittyCatfish gives you a simple interface for setting up catfish ads. Create as many as you want and set style and placement for each ad on your site.
New feature: shortcode trigger. Add the [kittycatfish_trigger] shortcode to your post or page content, and the ad will appear when the user scrolls to that point.
Standard content filters added; now you can do things like add shortcodes to the ad's content.