Gone - An ephemeral to-do list
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
RescueTime - Time management software that shows you how you spend your time & provides tools to help you be more productive.
Check - Check is a unit testing framework for C, which runs on environments such as GNU/Linux, GNU/Hurd, BSD, and Mac OSX.
Things - Things is an easy to use task manager.
Daily Routine - iOS app that schedules your day into key tasks