Oh the list is and was endless. When I was a young teen, I was buying singles and my older brother told me to buy albums. So if I ever liked a song by someone, I always investigated the albums. But there are so many artists/groups, someone will always fall through the gap. Plus now with so many songs/music being accessible....
But also, my library is over 10K songs. I'll have to see if there is a 'least listened to' list in JRiver,