Chemo Fingers!
I was watching an episode of CSI, and one of the victims in the show was shown to have transverse white lines across his fingernails. The show went on to say that it was a side effect of heavy metal poisoning, and the lines on the fingernails represented separate significant events of poisoning of the victim.
I happened to look down at my own fingernails and, wouldn't you know it, I have transverse white lines on all 10 fingernails (didn't check toes). One of my fingers is shown on the right. We had trouble finding a camera that could take good close up photos, and the lines are actually more pronounced in real life than shown here.
As it turns out, CSI was correct about the causes of the white lines. They are results of heavy metal poisoning (which I don't have), and also caused by fever, liver or heart disease, iron deficiencies, and a number of similar conditions. As it turns out, the chemotherapy treatment I received caused me to become anemic during treatment.
They tested me before entering into each phase of chemotherapy, and going into the final round the doctor said my counts (anemia) were low enough that I might have to get daily injections to combat it so treatment could continue. Of course, I talked him out of such a course.
Notice there are three lines on the fingernail above, one for each cycle of chemotherapy. If I can find time, Capt's McCall and Rutledge and I will perform an image analysis of the fingernails and attempt to determine the exact times these events occurred, although I doubt if any of us would be surprised of the results :)
Edit - Thanks to Jeff I know I was heavy metal poisoned!!