I’m not much of a fan of Ning but this The Mistake Bank site seems like an interesting site.
The Mistake Bank is a place to share stories of mistakes people have made in their lives and careers. After you sign up, you can contribute videos or blog posts recounting your mistakes that you think others could learn from. Start a forum topic or participate in an existing forum.
Obviously top 10 lists are a positive and quick-feed learning tool, but what about the case study approach analyzing “learning through failure?”