Heat a grill until medium hot, or heat the broiler. In a large bowl, combine the melted butter and brown sugar. Add all fruit, and toss.
Fold the edges of a piece of heavy-duty aluminum foil to form a shallow baking pan, and place on grill. Arrange the fruit, cut sides down, on the foil. Cook fruit until browned and caramelized around the edges, rearranging occasionally to prevent burning. Turn the fruit over, and repeat; serve warm.