Karma is ... sort of a form reputation currency. If you think someone posted something particularly informative or useful or just plain awesome, you can click on the "karma" button over on the bottom left of their post to grant them some karma.
A question of my own, at least partly serious: What is "women's fiction"? Can men read it? Can women read other fiction? Is there something about it that makes it gender-specific? Am I reading the wrong things? And what do the people read whose bodies or minds don't fit into either role? Give me a good explanation and I'll demonstrate the whole karma thing.