This is a quick and easy marinade that uses fresh rosemary and lemon to bring the taste of summer to your grilled chicken. If you can do this early in the day, that's ideal; if not, one hour of marinating can give you that extra flavor.
Trim any extra skin or fat off the chicken and put them in a one gallon ziplock bag. Measure out the olive oil and pour into a small bowl. Strip the rosemary leaves off the twigs, and do a "rough chop" (you want them to be about 1/2-inch in length); set 1 tablespoon of the rosemary aside (1/2 teaspoon if using dried). Crush the garlic with the side of a knife or the heel of your hand. Grate the lemon on a box- or hand-grater, reserving the rest of the lemon. Add the rosemary, garlic, and lemon peel to the olive oil, pour in with the chicken, press out air bubbles, and seal the bag. Put the bag in a small dish with sides and keep in the fridge until ready (this minimizes the risk of contaminating the rest of the fridge).
As the grill heats up, mince the reserved rosemary so that it is a little smaller, maybe 1/4 inch. Take the chicken out of the marinade and brush off most of the rosemary, garlic and lemon peel, leaving a few pieces clinging to the meat (a little bit of burned, crunchy rosemary goes a long way). Lay the chicken out on the pan and salt and pepper both sides. Cover the pan with plastic wrap and microwave the chicken until it just starts to cook (3 minutes on high, depending on your machine)--this fights chicken's nasty habit of staying raw inside even when the outside is burnt.
Take the chicken out of the microwave, brush with a little additional marinade, and grill until done, cooking each side twice. (For extra flavor, toss the rosemary twigs onto the fire just before you take the chicken off the grill--the smoke adds a great smell.) Before serving, sprinkle the chopped rosemary and spritz a little lemon juice over the chicken.