awesome - A dynamic window manager for the X Window System developed in the C and Lua programming languages.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Wonder - Your personal research assistant
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Shrowze - The human personal assistant you summon by text.
Remember The Milk - Remember The Milk is a task and time management application for mobile devices.