SnagIt is a great program for capturing and annotating pictures of your screen in order to illustrate concepts of any kind. For example, you can use it to help explain how to access a part of your course in BlackBoard. Or, you can use it to take pictures from a specialized application or website in order to provide illustrations for a presentation or for some other purpose. SnagIt can also take simple videos, including narrated videos, if you wish.
Along with Camtasia, SnagIt is available for installation campus-wide on all Purdue-owned computers. Review http://www.itap.purdue.edu/learning/tools/snagit/ for specifics and on how to obtain a copy.