I've seen a couple of web sites that had a few of those. One was the Ripoff Report. However, I'd be careful about what you post. If you post something that is libelous, you could face a lawsuit from the person in question. If you blog it, courts are more lenient about perceiving it as opinion rather than being posted as fact, but using another website might be perceived as you claiming fact and therefore defaming the person. Instead of using the Ripoff Report, you may want to use LiveJournal or MySpace. Wikipedia is used for facts and famous people, so it wouldn't be appropriate to use for your purposes.
