After the article Best add-ons for osCommerce, we come with another list of useful contributions that will help your osCommerce to save your time, upsell, increase conversion,  generate statistics and improve the design of your pages:

Buy_Two_Module – allows you to bundle 2 products in order to sell more. In the product A page you’ll have a recommendation box to buy product A + product B together at a discounted price. This module shows also how much you save buying the 2 products together than separated, and when you click the …