I used this tool extensively for my main presentation for the Time4 Online Conference and I don't know what I would have done without it! It allowed me to show exactly what the kids were talking about for each part of the presentation. Seeing the blogs etc in action as we were talking about them was really useful and also provided interesting visuals for people who have never visited our sites before. I also showed how everything we do is linked to our main class blog so there's only one URL needed to access everything.
iShow U is fantastic as it "allows you to capture and record anything you can see on your screen, along with audio from a compatibe source (like a microphone) as well as any audio from the mac itself." (yes it's mac only) The resulting files saves as a Quicktime movie which you can use in a multitude of ways.
I had previously tried the free version of iShowU - where you get to try it but GIANT green lettering appears over your movie. I liked it so much I decided to bite the bullet and buy the full version of the programme - only to find out how surprisingly cheap it was (it was only $28.40).
Now I really enjoy it because when people ask me to help them with something I can create a quicktime movie to SHOW them rather than typing a huge response or making a help sheet. Very useful and something I think is going to save me a lot of time. I see Greg from Outram has also discovered the joys of iShowU.
If you're on a mac and wish to be doing things like this... definitely check it out!