Very awesome! Interestingly, in both Chrome and Firefox, the song stops playing ("mostly") if you switch to a different tab. I say "mostly" because Chrome seems to play a single note every 10-20 seconds even with the tab backgrounded.

A cleaner way may be to allow the play() method to accept a plain JS array of notes:

  var notes = ['D#5', 1/4, 'E5', 1/4];
             or
  var notes = [['D#5', 1/4], ['E5', 1/4]];

  beeplay().play(notes);

CoffeeCollider is a coffeescript clone of SuperCollider, it has a lot of options for subtractive/additive/fm/granular synthesis and algorithmic sequencing/composition.

http://mohayonao.github.io/CoffeeCollider/

Flocking might interest you: http://flockingjs.org/

I remember in PASCAL with the sound() function:

  sound(100);
  delay(3000);
  nosound;

You mean like this[0] one?

[0]: http://tracker.stagas.com/