Three.do is a simple to-do list that forces you to choose your most three important tasks for the day and helps you focus to get them done.
"In any given day there are 100 reasonable things that you could work on. It's easy to get pulled into a fire on number 7, or even to spend time at a networking event or something like that that probably ranks in the mid-90s.
The founders that are really successful are relentless about making sure they get to their top two or three priorities each day, and ignoring other items."
- Sam Altman, President YCombinator