Go to parent folder in Mac OS X Finder

up.app

(*
 Script: up.app
 
 This script sets the target of the Finder window to the
 parent of the current target of the Finder window.
 
 Installation:
 
 1. Paste this script in Script editor
 2. Save it as an application - ~/scripts/finder/up.app
 3. Drag and drop up.app onto the Finder widow toolbar.
 
 @author Sandip V. Chitale
 @version 1.0
 @date 1/1/2009
*)
tell application "Finder"
 set target of front window to (parent of target of front window)
end tell