Some projects, like putting up a storage shed, involve a lot of nailing. This nailing can be done with a hammer, but can go much more quickly and easily using a nail gun, a tool that is no longer just for professionals.
You can purchase a starter set, including a compressor, hose, and a small nail gun for around $200. They are also available to rent.
Nail guns come in a number of different styles, shapes, and sizes. A framing nailer is best for rough framing work while finishing nailers use nails with very small heads. For roofing jobs you can use a roofing nailer, which drives in very short, large headed roofing nails. And for those who don't want to be held back by a cord, there is even a nailer that doesn't require a compressor or hose. This gun uses butane, which fuels a small explosion inside the cylinder that drives the nail into the wood.
Modern nail guns have a lot of safety features built in. They'll also save you a lot of wear and tear on your shoulder, elbow, and thumb.