I recently discovered Dr. Explain which is great for creating user interface documentation. It goes in and breaks all the user interface elements (buttons, menu items, edit boxes, etc.) out from your running application and then extracts any meta information it can from them to start your documentation (see screen shot). Then all you have to do is remove or tweak the items it found and edit the descriptions. Produces really professional user interface documentation really quickly. It also has all the other end user help documentation features you would expect.
This screen shot shows you one of the images it creates for you. This was created by pointing it at a preferences window. It then adds the little numbered blue boxes on the visible user controls. It also extracts the text and control type information (button, check box, etc.) as well as other meta information. These images can be made clickable too, to allow drill down from the screen shot.
This feature really blew me away. It might not be the best over all, but this one feature was pretty amazing.