Mix mayonnaise, curry powder, cilantro and salt in a medium bowl to combine. Mix in the shrimp, celery, bell pepper and green onion. Cut each avocado in half lengthwise; remove the pits. Trim a little from the bottom of each avocado so that they sit straight. Set a half avocado on each of 4 plates; brush with the lime juice. Divide and mound the shrimp mixture on top of the avocados and serve. Looking for something different? Divide and stuff the shrimp salad into four ripe papaya halves, seeds removed. Or, make shrimp and crab stuffed avocados by replacing half the shrimp with fresh crabmeat.