A simple plugin with one action: Play sound.
It uses html5 audio, so it should be able to play ogg, mp3 and wav files if the browser you use has it implemented.
It only works with exported projects right now. Any sound files you use need to be in the same folder as the exported project.
No sound will be played if you just preview the project. The preview can't find the files. I have no solution for this atm.
Download:
http://dl.dropbox.com/u/5426011/c2/simple%20c2%20sound%20plugin.zip
To install extract to the "Construct2-Win32\exporters\html5\plugins\" directory.
Feel free to modify.