Walkaround - Walkaround is a variant of Wave, based on the Apache Wave code base, that runs on App Engine.
RetailMenot - The RetailMeNot mobile app allows you to find deals on the go for both online shopping and in store shopping.
Slack - A messaging app for teams who see through the Earth!
Slickdeals.net - Slickdeals: The Best Deals, Coupons & Discounts on everything
Rizzoma - Email and IM are linear contextless communication tools.
Honey - Honey is a browser extension that automatically finds and applies coupon codes at checkout with a single click.