Human immunodeficiency virus (HIV)
A 3-D illuminated representation of what the Human immunodeficiency virus (HIV) looks like. Found in a display case in the "Keep Your Species Alive" section of the Hall of Human Evolution at the National Museum of Natural History. The display case showed many of the germs, bacteria, and virii that have killed significant portions of the human population over the millennia.
Even though what this model represents is a cause for concern, I think the model is quite pretty. Eh, I'm just weird.
UPDATE: Found the HIV model on a Serbian website about HIV, HIV awareness, and safe sex. This was kind of cool (considering where I currently work). ;-)