The Role Based UP / Cross Sells extension allows you to link products together based on the user role.
Up-sells are products which you recommend instead of the currently viewed product, for example, products that are more profitable or better quality or more expensive. Depending on your site’s template these products will display on the single product page underneath the product’s description
Cross-sells are products which you promote in the cart, based on the current product. Depending on your site’s template they will display on the cart page underneath the cart products table with a thumbnail image.