Is dua allowed after khutba?

I would like to know, whether it is allowed to make dua after the Khutba (is it called sermon?) given by any Iman (say in Friday prayer, Eid prayers). I have heard different views from different people as to some say *dua* is not to be made after the khutba, and some say it is one of the moments when your *dua* gets accepted. But, these views were never supported by any reference. Can anyone elaborate on this point with proper reference to authentic sources?