If you're a devotee of the French press, then a burr grinder is really a required accessory. It grinds coffee into evenly-sized bits, instead of smashing it randomly into an assortment of grains and fine powder. The difference between using a burr grinder and not is really noticeable, and when I started using this one I immediately began to enjoy French press coffee a lot more.
You can spend a lot of money on burr grinders, but this basic model from Capresso has been in use in my household for several years, and it does a great job. It's plastic and not particularly good-looking, but it blends into the background, and helps make a darn good cup of coffee every morning.