I remember reading somewhere that drastic ridging and changes in fingernails is symptomatic of some condition. Saw a pt the other day who had this and it brought it up. Can't remember what it was, but this gal's nail beds were really, really gnarly for about the bottom 1/8" of her nail.
Fingernails can tell you much about a person's health, although obviously not always specific or sensitive for particular diseases.
I wouldn't trust this site for a medical diagnosis since it is a site devoted to "acrylic nail enhancement", but it does have pictures with interesting facts about how some diseases present in the nail/nail bed:
http://hooked-on-nails.com/naildisorders.html
tc
-B