shaktool's synthesizer code in beepbox from actionscript to javascript. Most of the effort was the sad, sad task of stripping all the type information off. Check it out: http://jcreed.org/js/beepboxjs(you can also affix a #urlfragment from beepbox to that url to play songs other than the default, e.g.
like so)
I note, interestingly, how much the performance of the underlying machine seems to affect how small I can make the web audio context buffer size before shit starts skipping. My old creaky desktop machine needs 2048 samples, but my fancy fresh mac can get away with only 256, which seems to be the minimum the audio api will even let me attempt.