Student Systems and Educational Technologies offers Adobe Connect as a web-conferencing tool. At this time this is provided at no cost.
More information on how Adobe Connect works is available at: http://connect.johnshopkins.edu/welcome/
Johns Hopkins is currently licensed for 500 simultaneous or concurrent users of the Adobe Connect server. It can support two meetings of 250 users running at the same time, or five meetings of 100 users, and so on. Once there are 500 users total on the Adobe Connect server, no additional users will be able to join a current meeting.