OpenCart - A free shopping cart system. OpenCart is an open source PHP-based online e-commerce solution.s
Balto - Easy feedback with screenshot / videos for your beta apps
PayKickstart - PayKickstart is the ultimate shopping cart and affiliate management platform, empowering online Entrepreneurs and digital publishers with the tools to sell their products online.
buddybuild - Buddybuild ties together continuous integration, continuous delivery and an iterative feedback solution into a single, seamless system. With buddybuild, you can focus on what matters most: creating awesome apps.
Gumroad - An all-in-one solution to sell your work and grow your audience.
Twitter Audience Insights - Loads of info about your followers, their interests, & more