Duke is the second biggest feeder to Chicago Booth - http://poetsandquants.com/2011/10/06/top-feeder-colleges-to-chicago-booth/2/
The third biggest feeder to Columbia - http://poetsandquants.com/2011/09/07/top-feeder-schools-to-columbia-business-school/
Second biggest at Tuck (Dartmouth) - http://poetsandquants.com/2011/09/14/top-feeder-colleges-to-dartmouths-tuck-school/2/
Top 10 (8th) at HBS - http://poetsandquants.com/2011/08/15/top-feeder-colleges-to-harvard-business-school/2/
Top 10 (9th) at Stanford - http://poetsandquants.com/2012/05/30/top-feeder-colleges-to-stanford-b-school/2/