I’m not sure that I’d call these reviews (they aren’t really critical), but Farhad Manjoo has identified some apps that can be helpful in delivering your presentations. I’d particularly recommend having a remote control app– they’re easy to use and much cheaper than buying a separate piece of hardware.
On the opposite end of the spectrum, I’m not convinced it’s a great idea to turn your iPad into a teleprompter for a live speech. Reading to an audience and being able to keep them awake isn’t a skill most of us have. Even experienced politicians aren’t very good at it– few of them sound natural when they’re reading from those things. If you’re looking for something that can help keep your talk on track, I’d suggest just having a simple outline handy where you can glance at it as necessary.
One place where I have found it useful to mock up something like a teleprompter is when I’ve been doing webinars or recording a video. I’ve simply created slides with a word or two on each of them that reminds me of my next point and displayed them on my monitor or my iPad placed right next to the camera, where the audience can’t see it. That way I can advance the slide/teleprompter with a remote control (my iPhone) hidden in my hand and look like I’m speaking directly to the audience the whole time.
It works really well as long as you don’t spend the whole talk looking slightly off-camera, which can make you appear uninterested, distracted, or slightly crazy.