1Heat gas or charcoal grill.
2Sprinkle shrimp evenly with chili powder; set aside. Spray grill rack with cooking spray. Place corn on grill over medium heat. Cover grill; cook 12 minutes, turning occasionally. Add shrimp to grill for last 6 minutes of cooking time; cook, turning once, until shrimp are pink. Cut kernels from ears of corn. Discard cobs. In small bowl, stir lime juice, oil, honey, salt, cumin and pepper with whisk; set aside.
3In large bowl, stir together shrimp, corn, lettuce and tomatoes; drizzle with dressing and toss well. Add avocado; toss gently. Serve immediately.