There are a lot of screenshare apps out there these days. Most folk I know either use Google Plus Hangouts (requires a GMail account) or Skype (requires a download and installation rights on your machine), but there really are so many many more. What is harder to find are apps to screenshare from your iPad. Or iPhone. Or both. Or even ALL of the above – computer, phone, tablet …
Join Me lets you broadcast from all of these, and access a
presentation on any of these. You can watch a presentation in a browser window (no download) without an account. The difference is what you can do free. You can watch for free on any of them, but to broadcast or share your screen from the iPad requires the Pro version. It isn’t exorbitant, but it isn’t cheap either. For the free version, you can still broadcast / screencast from a desktop computer, for up to 250 folk. I think that’s still pretty useful and worth checking out.