meSing.js : meSing.js is a JavaScript singing synthesis library that uses the Web Audio API's DSP capabilities in conjunction with the meSpeak.js speech synthesis...
SoundManager 2 : Using HTML5 and Flash, SoundManager 2 provides reliable cross-platform audio under a single JavaScript API.
jsmad : jsmad is a pure javascript MP3 decoder, based on libmad, with an ID3 decoder written from scratch.
dancer.js : dancer.js is a high-level audio API, usable with both Mozilla's Audio Data API and Webkit's Web Audio API with flash fallback, designed to make sweet ...
Essentia : Open-source library and tools for audio and music analysis, description and synthesis
An interface for the Web Audio API that supports rhythms, multiple instruments, repeating sections, and complex time signatures.