Captivate

This software is amazingly easy to use and creates very professional looking final products.  It is quite expensive, and the output is rendered into shockwave (Flash) output. I believe you can also make movies and load them into YouTube. The advantage of using Flash output is that you can create interactivity very easily. You can create drag-and-drop exercises, multiple-choice questions, live links, and a host of other exercises.  It is available from Adobe Corporation.