initially I wanted to understand how webMIDI works, but then I tried different web things like web Audio, webGL and some audio visualizer. I also implemented Butterchurn (ButterChurn is a WebGL implementation of the Winamp Milkdrop 2 visualizer).
The website listens to MIDI and plays gm MIDI wavetable sounds (I did not implement the best soundfont yet...).
Really nice possibilities with web Audio and MIDI.