when i was in high school WAAAY back when, there was a guy who was in love with his bass (to the point where he was weird about it ). he showed it too me once. it was fretless, and may have been a 4-6 string. i wasnt into basses then, but what struck me as neat was the fret board. it was black, and seems slightly spongy, like dense neoprene. it seemed to indent slightly when he pressed the string down. did i just misperceive what it was, or was there actually flexible fretboards at one time. he may even be on this board. if you played fretless bass, and went to a small highschool in southern louisiana in the late 80's, then it might be you. btw, i am now "weird" about basses too!