Thaw the shrimp if they are frozen. Peel and devein the shrimp, leave the tails intact if you wish. Rinse shrimp and pat dry with paper towels. Set aside. In a small bowl, stir together ginger, lemon juice, oil, garlic, salt and pepper. Set this mixture aside. On 6 long skewers, alternately thread the pork, pineapple and nectarines, leaving about ¼ inch spaces between pieces. On the other 6 skewers, alternately thread shrimp and pineapple and nectarines leaving about ¼ inch spaces between pieces. Brush with some of the lemon juice mixture. Heat the barbecue and once it’s heated, grill the pork uncovered until it is no longer pink and the shrimp are opaque. Heat should be at medium/high. Turn the skewers occasionally and brush with lemon juice mixture. Allow about 10 minutes for the shrimp and about 15 minutes for the pork. Serve over a bed of mixed greens.