The first add-on music card for the Apple ][ was the ALF. Offering three voices with a high-resolution graphical user interface featuring a grand staff on which you placed notes using the game paddles, it was very sophisticated for the day.

Update September 2016:

There is a kit available on fleaBay to build a copy of the 9-voice ALF card. I haven’t seen the kit, but it looks like the real thing. ALF is a great way to do music on the Apple II. There’s lots of music out there, and it’s easy to program your own.

http://www.ebay.com/sch/plamenvaysilov/m.html?item=152247959912