Voxli offers browser-based group voice chat for gamers and teams.
Users of Voxli can voice chat with up to 200 people at a time without leaving the browser or setting up a voice server. Each group voice chat exists at a persistent URL, which can be shared with friends via email or IM. Voxli works on Windows and Mac, and supports push-to-talk (walkie talkie) functionality outside of the browser.
Voxli is currently free while it is in open beta.