What's your favorite life hack or productivity tip that you've discovered during your career that has helped you streamline your workflow?

http://Trello.com|Trello.com The mobile app is great too, my wife keeps my honeydo list there. I use it for various building projects around the house. I added my construction manager to it when building a house so he could keep up with all the items that needed resolution, they seemed to be going in one ear and out the other before I added him to a project to help him track.