Is there substitute for eggs

2 1/2 tablespoons of powdered egg substitute plus 2 1/2 tablespoons water OR 1/4 cup liquid egg substitute OR1/4 cup silken tofu pureed OR 3 tablespoons mayonnaise ORhalf a banana mashed with 1/2 teaspoon baking powder OR 1 tablespoon powdered flax seed soaked in 3 tablespoons water