Quick 'n' easy game sound effects generator.
A port of sfxr: http://www.drpetter.se/project_sfxr.html to HTML5.
Application: http://github.grumdrig.com/jsfxr/
Source code: https://github.com/grumdrig/jsfxr/
You'll find a more actively developed fork of this project, with a number of improvements and added features, running at http://sfxr.me/ with source code at https://github.com/chr15m/jsfxr .
riffwave.js: http://www.codebase.es/riffwave/
jquery-ui: http://jqueryui.com/