I've been spanked on occassions. I was an awful child, I deserved worse than I got. If I went back in time about 5-6 years (maybe longer)... I'd probably hunt down my younger self and give me the beating I so richly deserved.

That being said, I think their are better methods of punishing than a spanking. It's too... violent... and it can lead to more serious psychological/emotional issues. I have nothing at ALL against using pain-responce for discipline, I recommend pressure-point method (clean, easy, quick, and it gets the message across DURING the bad behavior, not after, which sets it in the child's mind far better).