Is there ONE thing that you can do to bring a giant number of listeners? Probably not, but the key values are the same - find out where your listeners hang out and get some information to them. "You need to move to where the food is..."
We are giving away "Dog Pack #3" from www.sounddogs.com to a School of Podcasting Listener who puts the School of Podcasting as a favorite at www.podcastpickle.com (members are already entered).