Scott Schiller created a useful flashlet SoundManager 2 a sound flash-js embed with an API to interface with your Web GUI.

SoundManager 2 introduction at Ajaxian.

These resources also may help you create the event sounds.

• SimplytheBest Free Sounds
• Freesound Project
• Audacity: Free Audio Editor and Recorder

Thanks for the resources and tools, it helped me build my web gadgets.