Sitecake - Drag and drop CMS for HTML websites. It's flat file CMS so it's pretty fast.
RetailMenot - The RetailMeNot mobile app allows you to find deals on the go for both online shopping and in store shopping.
Anchor CMS - Free and lightweight blogging system
Slickdeals.net - Slickdeals: The Best Deals, Coupons & Discounts on everything
Textpattern - Textpattern is an elegant content management system that is free, open source software.
Honey - Honey is a browser extension that automatically finds and applies coupon codes at checkout with a single click.