Cut eggs in half lengthwise. Remove yolks; set whites aside. In a small bowl, mash yolks. Add salsa, mayonnaise, onion, salt and pepper; mix well. Spoon into egg whites, or cut a small hole in the tip of a pastry bag or in a corner of a food-safe plastic bag. Transfer egg yolk mixture into bag; pipe into egg whites. Refrigerate.
Just before serving, place a tortilla chip in each egg half. If desired, serve with additional chips and salsa.