I haven’t put in activities where students entirely make their own questions (my favourites, so ask if you want links to any), but I have put in examples of other good things to do with discussion questions like giving different questions to student A and student B so they actually have to listen and testing them on the language of the questions after they’ve finished using them. Hoping to do a whole TEFL.net article on really exploiting discussion questions, but in the meantime here are the links to my own and others’ questions on every topic under the sun:

Discussion question worksheets and games