Dr. Mac's Prognosis "Grab It By The Hand"

Here’s one from the “I didn’t know you could do that” file:

In an Open dialog box or Save sheet, press Command and Option. The cursor turns into a grabber hand and you can drag the contents of the columns up and down. But wait, there’s more…

http://www.osxfaq.com/dailytips/04-2002/04-22.ws