For Drupal 6, you probably want to check the Amazon Store Module.
Amazon checkout module (Drupal 5 only at the moment) exposes an API that allows you to maintain a remote Amazon.com shopping cart on your site without dealing with the complexity of the Amazon ECS REST API and provides a checkout cart page and block.
This module allows your Drupal eCommerce shop to accept credit and debit card payments using the HSBC secure Cardholder Payment Interface (CPI) ePayments system. The Cardholder Payment Interface (CPI) is one of the products within HSBC Secure ePayments.
The ec_hsbc.module works with Drupal 6.x and Drupal eCommerce API version 4.x. Created by Dublin Drupaller.
Ubercart Donation Incentives allows a store owner to apply donation incentives to products.
This module provides Ubercart integration with the Malaysia payment gateway NetBuilder's NBePay, through onlinepayment.com.my website. This module requires Ubercart 2.
Features:
The UC Variable Price product feature allows you to turn any product in your Ubercart store into a variable priced product. Instead of using a fixed price entered by an administrator, customers can specify their own price for a product on the add to cart form. This makes it a useful module for donation sites! The module will automatically take care of the product add to cart shopping cart forms to accommodate the variable price field. It affords you some measure of control over the titles of various fields and also lets you specify a minimum and maximum price for any given product. Extra integration with Ubercart's product classes interface allows you to set default Variable Price product features on every product created of any given product class.
This module lets Ubercart customers mark an order as a gift during checkout and write a small message to go along with it. NOTE: Version 6.x-1.2+ requires Ubercart 6.x-2.3+
Store Administration -> Customers -> Gift RecipientsThis module adds a new condition to Ubercart's Conditional Actions that checks if an order is being delivered to a P.O. Box. This allows store administrators to restrict which shipping options are shown to customers who are using a P.O. Box. This is useful because some shipping carriers, such as UPS, won't always deliver to P.O. Boxes.
The UC Add to Cart Tweaks product feature allows you to alter ways the add to cart form behaves for any product in your Ubercart store. The current tweaks provided allow you to empty the shopping cart when the add to cart form is submitted and to alter the add to cart redirect URL. Extra integration with Ubercart's product classes interface allows you to set default Add to Cart Tweaks on every product created of any given product class.
The UC Ordered Products Reports module adds reports to user profiles and the administrator reports area showing all the ordered products by the specific user or by all users on the site. The fields on each report are configurable in the store report settings, along with the name of the tab used for the report on profile pages and the types of product nodes included on the report. The actual display of the report is sortable and filterable by year. Additionally, users may show the entire report on a single page to see a grand total of all purchased products, and administrators will have the option of exporting data from a report in a CSV file.
This module provides an Ubercart payment method to embed the payment services provided by Adyen. It efficiently integrates payments from various sources such as credit cards, bank transfers, PayPal and also mobile phones.
About Adyen
Credits
Development sponsored by SEIZ Apparel S.L.