This is from Alton Brown of the Food Network, but it has become a staple in our house.
6 C flour
1 1/2 tsp baking soda
3 tsp baking powder
1 Tbsp salt
2 Tbsp sugar
Combine all of the ingredients in a lidded container and shake to mix. Use mix within 3 months.
2 eggs, separated
2 C buttermilk (you can use 1 Tbsp of vinegar in a C of milk to make your own)
4 Tbsp melted butter
2 C pancake mix
Butter for greasing the griddle or pan
Whisk egg whites with buttermilk. In a separate bowl whisk the yolks with melted butter. Combine those two mixtures and add them to the pancake mix. Lightly butter the griddle or pan then wipe most of the butter off with a paper towel (I don't understand this step, but Alton is a master and doing things the way he suggests almost always yields fabulous results!) Cook the pancakes as you would any other pancake.