This technique works well if your site is done in a Notes database (it won't work w/ static HTML files that are served by Domino):
1. Create a database for your ads.
2. In the database's ad view, create the HTML for the image, text, and hyperlink.
3. In each document you want to put an ad on, use a @DbLookup with an @Random to select one of the items from the view.
4. Use passthrough HTML using "[" and "]" to pass the HTML through.
You can also put readernames fields on the ad documents so authenticated users get appropriate ads that are matched to their profiles.