In shallow dish, combine lime juice and brown sugar; mix well. Add pineapple, stir to coat, cover, and marinate 30 minutes or more. Meanwhile, prepare indoor or outdoor grill by brushing grill rack with oil and heating. Place fruit on grill rack and grill 2 to 3 minutes per side. Divide grilled pineapple evenly among four plates; top with a scoop of ice cream. Drizzle with chocolate sauce, if desired. Makes 4 servings.
*You may substitute sliced mangoes, peaches, or bananas.