Reeb is a free, open source teleprompter that scrolls when you talk. The code is public on GitHub for anyone to read, use or improve. It is not ready for everyone to install yet, so leave your details and I will send you the link the moment it is. No spam, and it stays free.
Reeb is free and open source, and it stays that way. If you want to help cover the Apple developer account so anyone can install it without a Mac, you can chip in at dodo.pe/reeb — 17 people already have. Totally optional, the app is free either way.