Thermometer

While cooking chicken today, I realized that I should probably invest in a thermometer. This purchase could vastly improve my cooking especially since I am red-green. To be honest, I have cooked steaks and burger rare not knowing until I bit into it; but, I wasn't turned down by this since it was so delicious. Even though it's tasty, it's probably not good for my health so I should probably cook it to recommended temperatures.

Poultry- 165

Red Meats- 145 (medium-rare with 3 minute rest period)

Ground Beef- 165

Do people actually use thermometers for cooking at home? Could it make a significant impact in my cook like my cast iron skillet has?