I've just been looking at some ELT publishers' sites. Most of them are offering extra worksheets and other goodies for use with their courses but I noticed that
OUP has gone one step further. For example, for Headway and
Intermediate Express they've put the tapescripts on line in Word format, explicitly so that teachers can make their own exercises with them. And for another book, I can't remember which, you can make cloze exercises from the texts.
As it's the texts (listening or reading) that I generally want to play about with, that for me solves the problem.