Hewlett-Packard provide free online classes covering a range of topic areas. These classes are usually 4-8 lessons long and can be completed at your own pace within the time-frame set by HP.
The lessons can be completed at your own convenience and include activities, reading, quizzes and assignments. HP also provide a Discussion Board for participants to communicate with each other for the duration of the course. The courses offered change over time so even if you do not want to do one on offer at the moment it is worth looking back later for new courses.