I stumbled upon this when i went to reddit.com http://www.reddit.com/r/todayilearned/comments/ed39q/til_how_to_make_google_beatbox_for_you/
,although i didn't think it would spread so quickly to youtube.com and countless other sites. I'm currently researching this a bit but i found this on tumblr http://googlebeatbox.tumblr.com/ with other peoples variations and an explanation of the sounds.
Over A Decade Later, Faith Hilling Remains A Powerful South Park Reference