Moodle is an open source (free) course delivery system that I use in all of my courses. Similar to products such as eCollege and WebCT (which cost a lot of money to use), Moodle allows teachers to provide web based course delivery to students for the cost of web hosting.

The Moodle community consists of head developer Martin Dougiamas and a cast of thousands of users. I highly recommend Moodle to anybody who has a web server available and is considering online course delivery. Have your nearest "tech geek" install it, you will be glad you did.