Screenjelly. Simple, fast, free public or private screencasting app. Nice big red shiny button. What more to say?
What is Screenjelly? Screenjelly records your screen activity with your voice so you can spread it via Twitter or email. Use it to quickly share cool apps or software tips, report a bug, or just show stuff you like. To start recording, click on the red button. No need to install or download anything!