CampFireNow has a voice chat over the browser. It seems that you do not need any plugins to install to get it working. This is a contrast to Gmail, where I needed to install an app.
I would like to implement a similar feature for my application. Is there a way to do this without requiring a plugin?
Flash or Java would be the only things that would be browser agnostic. Else, you definitely need a plugin, unless the specific browser provides you a method to record.