I really like CD Baby. I go to often and go to the folk genre and of course their are sub-headings such as Traditional folk, Appalachian folk, celtic and a lot more.

Then I will spend awhile listening to many artists that I am not familiar with but will listen to several of their songs from the Cd. I keep a little note pad to mark down the name of the artist, CD title, price for CD to refer to later when I have a list together of maybe 5-10 CD's that I really like and want to purchase. I usually will listen to several songs to determine if it is a CD that I really would like to buy or not.
I wouldn't have come to know of these artists if I hadn't heard them on CD Baby.

Some CD's I have heard are just ok but I have heard quite a few real gems of artists I had never heard of before.

Also, if you are looking for artist's similiar to well known artists you can type in their name, "Joan Baez" for example and it will bring up all the artists they feel have similiar sound or style.
It's not going to be exactly like Joan Baez but at least you can find artists who have similiar music to an artist you really like.