vRoom in Elluminate from LearnCentral (it's free). In order to keep students focused on the presentation rather than when their question will be answered, we'll use Edmodo as a backchannel with a student monitoring those questions. This will be something totally new for my students, so we will have to practice during the week. More on our experience next week! WooHoo!
photo: Madiyan Valley,Tajikistan by dwrawlinson