Teleprompt.me is a free online teleprompter that differs from the other ones at The Best Online Teleprompters.

The ones on that list move at a pre-set speed.  Teleprompt.me is voice-activated, so it scrolls as you say the words.  In addition, the words get dimmer as you say them, so it’s easy to see exactly where you are (just in case you get distracted).

Here’s a video from them: