Top keyboard shortcut of all time.
Spotlight search
This is the most time-saving, thus the most learning-worthy of all os X keyboard shortcuts.
The single most important shortcut to learn is Apple-spacebar.
This combination is a calculator, a dictionary, an application launcher, a system wide search mechanism. All combined into one.
Want to know the definition of the term "acre"? Apple-spacebar, type "acre" without the quotes into the spotlight search field that appears in the upper right corner of the screen. Notice that a dictionary icon appears which includes the beginning of the definition. While this entry is highlighted, tap the enter key to launch the dictionary application in a window displaying the complete results. Apple-q to quit the dicionary application.
Apple-spacebar again and notice that "acre" was saved from the previous invocation, allowing a quick search of local disk contents for that word as a search term. Use the up and down arrow keys to slide up and down the list. Tap enter key when the highlight covers a likely suspect to open that file in it's default app container.
Tap the esc in the upper left corner of the keyboard, once to back out of the last used search term, twice to close the spotlight search field.
I use this shortcut as an application launcher, calculator, and dictionary, in that order. As a speedy application launcher, it has no equal. To use as a calculator, type in the equation like 2*2 and watch the results display in real time. Jef Raskin would be proud.
