With newer browsers, you are finally able to implement some of the things you could do in flash years ago, without requiring browser plugins. I created Audio Grid as an experiment to explore this fact.
soundfont2mp3 - a command line utility that lets you extract single note mp3s from soundfont files.
timbre.soundfont.js - play soundfont urls using timbre.js
timbre.mp3_decode.js - a timbre.js plugin that decodes mp3s using jsmad
You can see a demo of Audio Grid by clicking on the image below: