EZ PayPal gets you started with your online business. Use PayPal IPN, sell digital goods with instant download, and no carts. Official PayPal Partner.
All in one WordPress plugin for selling digital downloads. It allows you to sell digital downloads via PayPal and manage orders from WP dashboard.
Monetize your blog by selling text links using paypal subscriptions
With Enroll via IPN you can send a follow up email to your paypal customer and let them opt-in into a product specific customer newsletter.
Simple to use invoicing system that can intergrate with Paypal. Very simple, very flexble.