Here are a few really good synths of scientific images in Photosynth. You can find others using Microscopes or Biology. And there is even a Dissected Cat if you have a strong stomach.
Obelia, polyps, golangia by ppberk
Micrographs of powder coating material by SynthSets
Frog Kidney by ppberk
Cross Posted from Dan Fay's Blog (http://blogs.msdn.com/dan_fay)