We are using vitero for our web based seminars comprising working groups from all over Europe. Besides providing excellent synchronous communication, vitero is capable of giving an extremely authentic representation of each participant, which is very important for achieving student centered learning and taking advantage of methods supposed to activate learning. Also, participants can take the role of a moderator or presenter during the sessions, what makes learning increasingly effective.
And finally, vitero is great for creating sub-groups during sessions, what gives us great freedom for structuring our seminars appropriately.