Streaks - The to-do list that helps you form good habits.
RetailMenot - The RetailMeNot mobile app allows you to find deals on the go for both online shopping and in store shopping.
Gone - An ephemeral to-do list
Slickdeals.net - Slickdeals: The Best Deals, Coupons & Discounts on everything
The ToDon't List - A to-do list for avoiding the things you shouldn't be doing
Honey - Honey is a browser extension that automatically finds and applies coupon codes at checkout with a single click.