Discount Code Generator allows site admins to generate discount codes in bulk and then export them directly to CSV

Discounts Pro gives you the ability to create advanced discounts that are automatically applied to the checkout screen based on specific conditions. In just minutes, you can create a discount that automatically gives 20% off to all logged in users, or all logged in users that have a certain user role. You can create discounts that give a discount to all customers that purchase specific products together, or even customers that purchase 5 or more products at once. With seven distinct discount types, you can create just about any kind of automatic discount you can imagine.

Your checkout is the most important part of your store. Make sure you’re capturing all the important information you need from your customers with custom checkout fields. Use Checkout Fields Manager to easily add new text fields, drop-downs, file upload capability, checkboxes, and other field types to your checkout with the intuitive drag-and-drop interface. Give your customers an enhanced purchase experience with fields that are unique to your business.

Stripe Green Downloads is a plugin that allows to sell files and accept major credit cards (through Stripe). Workflow is handled by smart CSS3 button: customer click the button, submit credit card details and download file instantly.