Tracking down Turbosynth:
http://acapella.harmony-central.com/archive/index.php/t-1717183.html

Trent Reznor, techniques used for The Downward Spiral:
1) http://nothing.nin.net/int6.html
2) http://nothing.nin.net/int20.html
3) http://www.thegearpage.net/board/archive/index.php/t-293539.html

Community Suggestions:
http://www.thegearpage.net/board/archive/index.php/t-293539.html