The baking soda/peroxide/soap formula is the only thing that really works:
1 quart hydrogen peroxide
1/4 cup baking soda
1 to 2 teaspoons of liquid soap (you can add some warm water for big dogs or just increase all the quantities above.
Keep it out if the dog's eyes, leave it in for a half hour, rinse in warm water. Repeat if the dog still stinks, which it will. When the skunk odor gets into the nose or mouth, there's nothing you can do.
Be sure to take off the dog's collar, which probably stinks too. First time it happened to my dog, I left the collar on and couldn't figure out why she still smelled days later.
Good luck, it's a total drag.