I am sure you know about TED videos. This project looks really interesting--you can take videos and add commentary, questions and more for your classes by using videos of dynamic educators. Lots of potential.
Collaborize classroom looks very interesting and it's free. Encourages student engagement, shares lesson plans and more. Pretty strong endorsements of website as well. Worth checking out.
PresentationTube Recorder is a tool designed to record Ppts for 15 minutes--free, of course, though there is a paid version that allow more to be done. Worth a look