Soak bamboo skewers in water for 1/2 hour. Thread 4 shrimp onto each skewer,threading each shrimp through the tail end and then again through the head end; arrange on a large plate. In small bowl, whisk oil, rosemary, lemon zest, garlic, black pepper, pepper flakes and salt until combined; rub over shrimp. Marinate 30 minutes, in refrigerator, turning once.
For the Mango Salsa: In medium bowl, combine all salsa ingredients. Let stand at room temperature while shrimp are marinating.
Prepare an outdoor grill or preheat stovetop grill pan over medium-high heat. Grill shrimp 2 1/2 to 3 1/2 minutes per side until just cooked through (shrimp will be just barely opaque in thickest part when cut with a knife). Place a lemon wedge on end of each skewer. Serve with salsa.
Makes 4 servings