Lets add one more - A Yankee-style Screwdriver & Hex Driving Chuck from here.
Also jb93 - What exactly are the screws you're working on?
I would use an impact driver with the proper screwdriver tip.
That is commonly called a speed wrench. Sears Craftsman 9_44271 for 3/8" drive. But, hey what you want is a hand impact screwdriver. No self respecting outboard mechanic would dare be without one. It has a cam inside that rotates the bit when you whack it with a hammer. Greatest thing since sliced bread.