Even more is possible.
Snip and a "real" pen based device, such as a Surface device from Microsoft, allow a teacher to quickly and easily create Khan Academy style tutorials. This was discussed in the article at eschoolnews.com and ecampusnews.com.
This works well when a static background is all that is needed. More powerful software has been needed when scrolling backgrounds or different programs have needed to be demonstrated.
However, there is another solution that works as well as Snip, is free and leverages digital ink. I am working on a new article to highlight this solution. Hopefully it will be published in the near future.
Once you try them it is impossible to return to the old keyboard and mouse only devices. I still use a keyboard and mouse when they are the best solution to the task at hand, but i also need the pen based capabilities at times.