These might not be the six greatest singer-songwriters ever, but they are probably the six greatest singer-songwriters that far too few people know about. And they are certainly among my personal favorites.
Mark Germino (no website)
[Edit to add: The problem with lists like this is that someone always seems to get left off. I woke up this morning and it occurred to me that I had forgotten about Nashville's finest, David Olney (on myspace). It's only been a few times that I have been lucky to hear him live, but each time he has absolutely owned the room with his beautiful and stirring yarns of characters real and imagined.
One more than one occasion, I have brought a friend who had little or no interest in the artist and was just tagging along with me to tag along with me. Each time, by concert's end that friend would be asking me all kinds of questions about David Olney and where to buy his CDs. If for no other reason than "Jerusalem Tomorrow," he is one of the best that Nashville has.]