In a medium sized saucepan, mix butter or margarine, water and salt. Bring to a boil over medium heat. Add flour all at once and stir vigorously.
Cook and stir until mixture pulls away from sides of pot and forms a ball that does not seperate.
Remove from heat. Cool 5 minutes then add eggs, one at a time, beating with a wooden spoon after each addition. Beat until smooth.
Preheat oven to 400 degrees.
Drop batter by heaping tablespoon or with a pastry bag onto baking sheet, about 3 inches apart. Bake for 30 minutes or until golden brown.
Remove from oven. Split open and remove any soft dough inside. Cool on a wire rack.
Fill with your choice of pudding, whipped cream, fruit etc. Replace top and sprinkle with powdered sugar or whipped cream.
For Chocolate Eclairs pipe dough onto baking sheet with pastry tube making 4 inch strips before baking. When baked and cooled fill with pudding or whipped cream and top with melted chocolate.