Some great keyboard shortcuts. via Jonny Evans of Computerworld.
Command – Comma (,)
This is one of the least-known keyboard commands on a Mac, but it’s super useful. It works like this: You are working in an app, and you want to open the application’s Preferences. You can navigate to the Menu bar if you like and scroll through to access the Preferences. Or you can simply press Command-, (comma) to get to them in the fastest possible time.