It all depends on what you consider useful. I have several tools in my toolbox that are not used every day, but are very useful when they are needed. Some of them also come in many different versions or brand names. Here are a few goodies one should not be without.
http://www.garrettwade.com/hd-screw-...et/p/35N07.05/
http://www.garrettwade.com/innovativ...st/p/35N03.03/
http://www.walmart.com/ip/Dremel-400...-3-34/14299568
http://www.tequipment.net/Hakko936-RC-G.html