Wicked: The Life and Times of the Wicked Witch of the West, by Gregory Maguire (TPB, 1995, $2)
"When Dorothy triumphed over the Wicked Witch of the West in L. Frank Baum's classic tale, we heard only her side of the story. But what about her arch-nemesis, the mysterious Witch? Where did she come from? How did she become so wicked? And what is the true nature of evil?"
Just what we all need, another story of a misunderstood person.... er.... witch.
Look for it in the fiction section.