MacDailyNews - Apple and Mac News - Welcome Home: "Now for the ultimate: Hold down Command-Control-D as you move your cursor over multiple words and watch what happens! (Bonus secret: you can let go of the D key and as long as you continue holding Command-Control, it'll keep working.)

It works in text input boxes, too. So, no more misused, misspelled words for Tiger Safari users in your Reader Feedback comments, okay?"