You can add (a) page(s) which display(s) banners at random.

Custom Banners provides a simple interface to upload several banners and show a random or specific one to each visitor, using a shortcode.

Display random banners easily, random banners widget, banners before or after post content automatically, banners between post content, and more!.

Display user specified content in random or circular order, through a widget or shortcode.