I've been concerned with translating of a sense of teacher's personal presence into online course design; while this article is brief (and maybe over-dependent on a graphic), it nevertheless invites specific choices of format, teaching strategies, instructor roles, and type of technology, all to the end of suggesting an active and engaging professorial presence.
Although I am not completely enamored of the final proposed model, which I think oversimplifies the very issues their analysis distinguishes, I do find this article useful in giving names to a number of factors we have found ourselves discussing: e.g., learner-interface interaction, transaction v. interaction, interaction v. interactivity, provocateur v. academician. Useful for our ongoing conversation.