1. If you have to attach some fence pickets to horizontal boards, to prevent excessive vibration, consider using a big sledgehammer. Simply start the nail by tapping it with a regular hammer, and then place the sledgehammer behind the 2x4 to absorb the blow and to stop the vibrating.
2. If you have to do a lot of repetitive even-space nailing, for example, putting on a sub-floor with an evenly spaced frame, lay out your hammer and measure the distance needed with a tape measure. Simply mark the distance on the hammer with tape, and you have an automatic measuring device.
3. If you're putting up some crown molding, you know what a hassle it can be to pound in the nails, which can cause some dents in the molding if you miss. Instead, why not use some pegboard to prevent the damage. Simply start the nail gently, place the small piece of pegboard over the nail and then finish the job. No need to worry about dinging the molding because the pegboard acts as a perfect shield.