This is called a screw starter screwdriver and Harbor Freight has them but only included in a set with other screwdrivers, last time I checked. I also use the Bicycle Research spoke nipple driver mentioned above.
Originally Posted by
70sSanO
Last time I used this screwdriver. I have no idea where I got it.
John
Edit Added: I do remember grinding the typical screwdriver side flares straight and making the tip end thicker.