Preheat the broiler. In a small bowl, mix 3/4 teaspoon salt, 1/4 teaspoon pepper, and cinnamon. Sprinkle on the chicken. Put chicken, skin side down, on a broiler pan, and broil about 6 inches from the heat for 15 minutes. Turn chicken, and broil until skin is crisp and brown, about 15 minutes more.
Meanwhile, in a small bowl, stir together cucumber, yogurt, sour cream, cilantro, cumin, and 1/4 teaspoon each salt and pepper. Serve chicken hot, with raita on the side.