There have been quite a few times I’ve simply placed my iPhone camera into a microscope ocular, so I could snap an image of an affect I was seeing. Along the same lines, this is a PVC pipe-connection for your run of the mill point and shoot camera. The images won’t be measurable in any way, but it’s be nice to have this in a pinch!
http://makeprojects.com/Project/Scope-Photography-Rig/928/1
-Austin