Hubert, I was told about Steven Hassan's book, "Combatting cult mind control". I got it and read it last night. It is brilliant. He makes a distinction between 'deprogramming' and interventions. He's ethical.
He recommends that you stay in touch with your family member who is in a cult. Breaking ties make it that much harder to get them back. He offers techniques to make them think about 'the old days' and remember and get in touch with their feelings. I could see that it would be very effective.
Off topic, sorry, but it was appropriate I think :)