I know that S.M.A.R.T. is something that monitor the health of harddrives. When I found that Cygwin provided a program called smartmontools, I googled for it, and found the web page http://smartmontools.sourceforge.net/.
But what is smartmontools? What can it do? That's the answer I'm most interested in, both on the home page of smartmontools, and on the FAQ page. (I guess that the Linux Journal article that the web page linked to will be of some help.)