Along with the hammer, the screwdriver rules supreme in toolboxes across the country. This type of multi head screwdriver with replaceable bits is very useful. It comes with a set of replaceable heads for any type of screw fastener you're working with.
Usually the tool comes with at least a #2 flat blade and a Phillips head bit. If you chip a blade you can always get another replaceable bit. The only real issue with these tools is keeping track of the loose bits. But you find what works for you in terms of keeping the bits handy, and the tool is great.