I've also used Jing and really like it. Very easy to use and "integrates" with Screencast.com (also free), which means you can quickly create a video, publish to screencast.com (so they host it on their servers consuming their space and their bandwidth), and then just give people the URL. Very slick.
The one downside/limitation to be aware of is that you can only record up to 5 minutes. So you better talk fast
