A number of folks have been using Anymeeting-- which is an ad-supported conference software tool. To the credit of Anymeeting; it is a very good product for organizations and get-togethers who happen to maybe just host a webinar maybe once or twice and then be done.
For that, it's pretty good. There is something each user has to download, which can be annoying if users have firewalls that block downloads. But other than that it's a nifty little tool that people can use in a pinch.