Preheat the grill to medium and brush clean with a wire brush.
In a saucepan, combine the rum, sugar, orange and lime juices, and simmer, stirring, to dissolve the sugar. Let cool.
Place pineapple on the grill. Cook until lightly charred and golden, basting on both sides with the rum mixture, 6 to 8 minutes.
Remove from the heat and arrange 2 slices in each of 4 shallow bowls. Top the pineapples with a scoop of ice cream, drizzle a spoonful of the remaining rum glaze on top, and garnish with toasted coconut flakes. Serve immediately.
Yield: 4 servings