The Audience Network is DirecTV's in-house channel (formerly The 101); they carry reruns of some old HBO original series (Deadwood, Oz, The Wire), plus original shows that started elsewhere (Friday Night Lights from NBC, Damages from FX). Also, Dan Patrick's radio show that's simulcast on the Fox Sports regional networks originates from the Audience Network.
I've occasionally used DirecTV Everywhere, and the on-demand content, at least from HBO and Cinemax, is rather limited compared to what you get from the networks' on-demand website directly.