Designer Reagan Ray isolated the lettering from various jazz album covers for a bunch of artists and made an online gallery of little cards. I love the variety and colors.
But the most influential designer was probably Reid Miles, who created over 500 album covers for Blue Note Records. He pioneered the use of creatively-arranged type over monochromatic photography, which is a style that is still widely used in graphic design today.
Rather than post 100s of covers and posters, I wanted to isolate the lettering for easy browsing and analysis. There's a lot of lettering out there, and a lot I left out. I tried to cover most of the genre's significant musicians (and only pick one piece per artist), but if missed anything glaring, let me know.