ECO (Extra Customization Options for Ubercart) provides additional ("extra") options to customize Ubercart.
Please see a list of features below. Some of the functionality provided also includes a degree of integration with other contributed modules like Legal, Webform, and Ubercart Discount Coupons. Among the customization options are using URL parameters to auto-apply coupons in checkout, requiring new customers to choose a password, and integration with the Webform module to pre-populate address fields in checkout.
Among other things you can accomplish with ECO is to have a shopping experience that does involve a product page or add to cart button. For example, you could include a webform in a block, via Panels, or through Views, etc. in which you collect information and pass it through to Checkout along with adding a product to the cart automatically. The Webform module saves the data entered regardless of whether or not checkout is completed in Ubercart.