My favorite has to be ⌘+Space. It brings up Spotlight Search. I use it instead of the Dock to launch applications. It quickly adapts to your preferences. For in

My favorite has to be ⌘+Space. It brings up Spotlight Search. I use it instead of the Dock to launch applications. It quickly adapts to your preferences. For instance, after a few tries, it will learn that you want Digital Color Meter when you type 'dig'. So, you just type "⌘+Space dig Return", and the app starts. It's also useful to look up words quickly in Dictionary and to evaluate simple arithmetic expressions. That's all in addition to its normal use: searching your machine