The general idea of this (free) cloud/web/mobile app is simple. see your presentations anywhere. I think they called it “Webex for the iPad era” on their blog.
I haven’t used it in any high pressure live situations (ie in front of an audience i’m actually presenting to) yet, but I have done a couple of demo meetings with some coworkers, and it was awesome. Email or Upload the document to MightyMeeting so it appears in your library, open it on your mobile device (Android in my case) and choose to “start meeting now.” then you can invite people to join the meeting (via email, with the invites integrated into the app) and they can watch on their device (iPhone, for example) or on their PC through a web browser. It’s a really great app, and the “next slide” responsiveness was very high (here on the corporate network at the office.)
I highly recommend this for anyone who does presentations with any regularity.