join.me is an online service and standalone software alternative that allow users to share their screen with other people. Users can invite many persons to join their session and to watch the presentation. During a join.me session, users can chat and use audio (microphone), share files, allow all or specific users to use your screen or control your computer.
It allows to use multiple monitors and you can share a second monitor in live session, if you have one.
More features are available at paid upgrade, but with free version you can share screen, make internet calls, chat, send files, use multiple monitors and keep live meetings with 10 participants.
Remote users can use a PC, iPad/iPhone or Android devices.