I put together a longer promotional audio file for Missionary Talks last night. It can be used for podcasts that simply want a longer promo. But primarily I put it together for another podcaster who has a show specifically highlighting other shows. He plays these longer promotional files as a service. Ok, he calls it an Endless Ego Cavalcade, so maybe it is not such a service to the podcasters as much as it is a chance for other podcasters to get a big head and play their promo.
However you want to see it, the promo is available at Missionary Talks and can be used however you will.