As an example of the sort of thing you can do by combining a live radio show with facebook, check out https://www.facebook.com/groups/ciaran/
, which is the facebook group for Ciaran's show which I mentioned above.

Today from 5pm-7pm (UK time) his guest is a well known singer and singing teacher. So a day before the show he posted:

"DORRIS DISCUSSION- 9TH JUNE- HAVE YOU/WOULD YOU/COULD YOU EVER SING IN PUBLIC? My guest, Shona Brown, runs singing workshops and has started up several community choirs, including the UK's first prison choir!! So....I wanna know if YOU would ever do it. And, if you have, is it something you enjoy, or a nerve-wracking labour of love???"

The chat on that thread will form a key part of his show.