Ubercart - It is one of the best e-commerce solutions for Drupal users. It's free, extensible and very powerful that can help you create a secure and reliable online business. It not only provides dozens of integrated payment methods but also gives you user-friendly administration panels for complete control of your online shop. It also has a powerful API that lets you extract, analyze and store important financial data at your will. A robust activity logging system helps website owners keep a check on every event occurring on their website to detect any unusual or fraudulent transaction.
Drupal Commerce - This is yet another powerful and open source e-commerce module for Drupal-powered websites. Its strong social connectivity sub-module lets your customers share products and services on all popular social media platforms helping you getting more eyeballs for your offerings. It has a dynamic currency conversion and VAT calculation system that lets businesses across the world deploy it without any problem. Its flexible API lets you easily import and export all the important and sensitive data associated with all the monetary transactions.
Amazon Store - The name itself tells you that it brings Amazon products to your website. It uses 'Amazon Product Advertising API' to integrate a store with your Amazon associate ID so that you can earn your commissions selling products available on this popular online store. You can create custom product pages and can integrate a shopping cart with ease through this module. It also lets visitors search products on Amazon directly from within your shopping cart. You can customize your product pages based on different criteria.
Content Injector (formerly AdSense Injector) - This is one of the most flexible modules to insert different kinds of advertisements on your Drupal powered website. It uses various techniques to inject advert codes at desired locations without compromising speed and security. You can also use custom CSS from within the module to fine-tune the placements for better conversions. In fact, you can use this extension to insert simple text, HTML, JavaScript or any other type of content at different locations on the web page. You can also use it to insert ads in the middle of the content.
Classified Ads - As the name implies, this useful module can be used to turn your website into a full-fledged classified ad posting hub. Integrated payment system lets you collect revenue from advertisers automatically. It also has support for auto-renewal during the grace period, user-specific private ad lists and flexible list sorting to quickly find out relevant ads from the entire database. You can also customize notifications for advertisers to let them renew, cancel or update their listings. It also supports the integration of various other modules for more flexible ad-customization options.
Pay - This is a powerful and generic payment module that can be used with any other module to integrate a secure and reliable payment processing system. This excellent extension supports over half a dozen popular payment gateways which can be easily configured through a user-friendly API available within this plugin. You can collect and process payments on any web page through a simple web form coupled with custom payment processing logic. It lets you create from simple to very complex business rules while integrating the payment gateway.
Drupal Rooms - If you're running a hotel, guest house or a cafe, this Drupal module is made just for you. It lets you deploy a complete booking and room management solution in no time. You can create different categories and can apply various attributes for each room category. It includes a secure payment system that runs your hotel business smoothly without any worry to track bookings and related billings. Its powerful search facility lets executives find availability of rooms instantly. You can also maintain customer profiles in a separate database to facilitate fast bookings for returning customers.
Affiliate Store - This is a must-have plugin for affiliate marketers using Drupal for their marketing campaigns. Through this extension, you can easily integrate EarnHighWay affiliate store in an easy way. It lets you pick products from different categories that automatically create different product pages with associated payment gateways. The product URLs generated through this module are user-friendly that significantly increases the CTC resulting in more earnings for you. You can also customize the layout and theme of your product pages very easily through this plugin.
Faktura - This module provides a powerful invoicing system for Drupal websites. Apart from regular invoice processing, this extension can also export all your invoices in OpenOffice format for easy archiving and be reading. You can also create time reports through user-friendly wizards. In fact, you can use these time reports to automatically fill new invoices to speed up the entire process. Future versions of this plugin are also going to support recurring invoices and invoice delivery through secure email communication.
Wazala - It is yet another robust and flexible extension that lets you create your own online store powered by Wazala. It has tons of customization options to shape your online cart in literally infinite ways. It also has inbuilt support for major payment processing gateways. Wazala is available in 15 different languages making it an ideal candidate for providing the best shopping experience to different customer segments across the globe. It has one of the best administration interfaces with help wizards that make the entire customization and admin task, a cakewalk.