Preheat broiler (if desired). In a medium bowl, combine the tomato, corn, feta cheese, cilantro, lime juice, salt and pepper. Mix well and set aside.
Spoon the mixture over the top of the 4 avocado halves. If desired, place the stuffed avocados on a baking sheet and broil for 3 to 4 minutes. The peel can serve as a bowl. Scoop contents out with a spoon.