Technical demo of Chiptune.js.
No actual audio files have been used in this page, just AudioContext Oscillators and various other nodes. Noise channels are 1-second 22050hz js-generated sample buffers set on loop and modulated much the same way as the oscillators.
Thus far only Chrome supports AudioContext "properly" (the standard is still in progress...). I am told Firefox's nightly/beta builds also work. Safari claims to give me an AudioContext, but then pretends I don't exist and never asked it for anything as soon as I try to start an oscillator. Other browsers are likely to throw errors, but will hopefully at least alert to the nonexistance of AudioContext.

For the uninitiated, the music itself is an interpretation of Take On Me by a-ha (1985) which, apart from being an arrangement I never got around to on Nesglovphone, is probably the most awesome, technically amazing, and creatively inspired music videos of the era (no CG; all hand-rotoscoping). There is, as I have noted, no actual audio file to download for this page's arrangement, but the band and their lawyers would probably be happiest if you checked out the original on e.g. iTunes video or album, Amazon, etc.