Slice pears into 1/8-inch wedges, and squeeze lime juice over them. In a frying pan over medium heat, melt butter and stir in brown sugar. Stir in half of the rum. Add pear slices and cook about 3 minutes turning pears once. Sprinkle cinnamon on top. Pour remaining rum into separate saucepan and heat until it bubbles. Remove from heat. Ignite rum and pour over pears in fry pan; stir gently. Serve over vanilla ice cream. Garnish with lime wedges, if desired. Serves 6