Over at Memento Vivere, Rob has a post on the potential for podcasting in academe in general and Classics in particular ... just to expand on his 'guest lecturers' suggestion, I still think that entire conferences and/or panel sessions can/should be made available as podcasts. The technology required to do this sort of thing is readily available and the only problems I could see with it would be dealing with questions afterward (i.e. microphone set up) ...