One of the annoying features of the system-wide spell check on Mac's is the fact you have to grab your mouse, right-click the word, and then click again to select the word. Macworld shows off how accomplish the same thing with just the keyboard.
This trick works on any program that uses Apple's built-in spell checking system, which means the likes of TextEdit or Mail. You have to enable to options for it to work. Under Edit > Spelling and Grammar, make sure Check Spelling While Typing and Correct Spelling Automatically are checked. When you misspell a word, hit the space bar, then the left arrow, and a menu will drop down with spelling suggestions you can navigate to with the arrow keys. It's a handy way to keep your hands on the keyboard and off the mouse while typing.
It also goes well with our previously mentioned tip for hitting the Escape key when you're struggling with a word spelling. It doesn't work in every application, but it's worth trying in any program you use that relies on the built-in spell checker.
Correct spelling from the keyboard [Macworld]