Ask HN: What are your greatest productivity hacks?

In the last few months I started using a clipboard manager (Ditto) and I'll never go back. My 'clipboard anxiety' (did I leave something in the clipboard? can I copy this? better open notepad and Ctrl+V just to be sure...) is gone, and I can copy stuff with reckless abandon.

This got me wondering, what are some of the other productivity hacks like this that I'm missing out on? I already use AutoHotKey and rave about it to anyone who will listen, but there must be other ways to improve my workflow.

What productivity hacks have changed your life?