If you want to be staggered by the by the sheer number of bacteria that live in and on us, by the fact that different parts of our bodies are inhabited by different bacteria, by the fact that different people host different communities and that as we change (e.g. by aging) we take on new fellow travellers, read "Structure, function and diversity of the healthy human microbiome" in this week's Nature. If you want to be staggered by the effort that has gone in to the Human Microbiome Project read "A framework for human microbiome research", also in Nature. But for the back story on the really cool illustration on the journal's cover click here.
And what does all this have to do with mass torts? If you have to ask, you haven't been paying attention. :)