Came across this database today. Organized by Vertical, Horizontal, Mixed Modes and then by NES licensed, unlicensed, Famicom, and Disk System. Also has rom hacks and homebrews.
May be old news to some, but it was a great find for me.
NES Artifacts Blog:
http://nesartifacts.blogspot.com/p/nes-shmup-guide.html?m=1