I am using 'Discussions A-Z, A resource book of speaking activities' published by Cambridge. It's expensive, but worth it to me as I've been able to use it a lot in my training.
It has photocopiable pages. I'm teaching an IELTS class and will photocopy 3 pages for the students. During the week, the students will call me three times and we'll do a page each time. This is an English by telephone course and it works great.
The book has lots of little questions formed around a topic. For example:
What would life be like if we didn't have clocks? Would there be any advantages? etc, etc.
Why do we need families?
Is the family ever likely to disappear as an institution?
Should the mother or the father be the head of the family?
Which is the easiest job?
babysitter, dentist, football player, teacher
The most tiring?
doctor, farmer, miner, tip model
There's about 50 units. Each unit has teacher's instructions. My students like it very much.
I'm doing this training by phone, partially as an experiment. I've found it to go surprisingly well. I was afraid there might be trouble with clarity over the phone line but it has been very clear. Also, the student gets one-on-one conversation time with me, howbeit only 15 minutes a go.