Snap! makes it easy to record audio and video narration for your Powerpoint presentations. It also lets you create interactive quizzes and surveys.
You can export the result as either a standalone Flash presentation for use on any web site, or a SCORM module that can be imported into just about any course management system.
It's very similar to Adobe Presenter, except that it costs only $99 rather than $500.
Free trial here.
Demo by me here.