Saw this nice online app via someone’s tweet and I am still pinching myself to believe it is free. Its called screenr; simple and effective app. Basically you use it to record the actions of your screen (hence its name) and it can record audio if you have audio input. The real beauty of it is its not tied to any one platform as you use it via a browser and can save files in multiple formats, publish to youtube and save the files (you dont need to download your recordings if you are not blessed with abundant drive space).
screenr screen shot
I can see this one becoming a big hit with those who create tutorials, you can check it out here.