Which server has the most variety you've come across? I only ask because there's a lot of independent Jazz groups I've discovered, but I can't find them anywhere. I don't mind buying some of their albums, but if I could find one or two, I'd be a happy boy.

I've found Soulseek very good for find rare music.

Me too, soulseek finds a lot of rare music
Sometimes Emule

That's about the only thing I could think of.