1) Carefully scoop out the pulp from the peach halves, leaving a 1/4 inch thick shell. (I use a grapefruit knife to make this job a snap.) Chop the pulp and set it aside. Brush the peach shells with 2 teaspoons lime juice to prevent browning. Set aside.
2) Combine the reserved pulp, the berries, the peach nectar, the remaining teaspoon of lime juice, and the almond extract in a small bowl. Toss gently to coat. If it tastes a little too tart, add a packet of Splenda. Spoon 3 tablespoons of the peach-berry mixture into each peach shell. Serve on curly-leaf lettuce leaves, if desired.