I think spanking is okay under certain circumstances.
I feel spanking is appropriate when a child deliberately disobeys you after warnings and time out etc. I also believe it is okay when a child puts themselves in harms way. It can make a real impact if done the right way. I call this direct and purposeful disobedience.
Do not spank in anger. Do not walk up behind your child and swat them when they do not know it is coming.
Sit your child next to you or on your lap. Explain the action that is about to take place and it is the consequence of their behavior. Stress that you love your child but you did not like the behavior.
I will tell my child what to expect and how many swats (usually 2) and do the deed. When this type of discipline is administered, the offense usually ceases.
Many of you will cry child abuse etc. But if you want proof, look at the people of our society that were raised on Dr. Spock and anything goes. Just look at our future leaders. They, most likely, have not had to suffer consequences for their poor behavior. The world is a complete mess and it has become this way over the years partially because of lack of parental involvement, no limitations for their children, and a lack of morality.