Advanced Cross Sells lets your show additional products on your product pages, usually preceded by a title like "You may also be interested in". This allows you to show more products to your visitors, increasing the likelihood of making a sale and of increasing the size of your average sale.
This cross sell product is styled with CSS, making it extremely flexible. It also allows you to choose exactly which items to display as cross sells on each page, or just allow the built in automated feature list other products in the same section. You can also use the automated feature but have an exclude list of products that will not be shown. Finally, any item set to non-orderable will never be displayed.