I’m currently taking the free Intro to Databases course taught by the excellent Professor Widom. The course consists of video lectures with homework exercises, quizzes and midterms. There is also a helpful Q&A forum for students when you get stuck.
In the beginning of 2012, there are more free online courses available, including:
The classes are high quality and perfect for you if you can spend more than a few hours a week per course. As they are free, the courses don’t offer any official Stanford certificates, grades, or credit. You do get a Statement of Accomplishment from the instructor.
I’d recommend these courses to anyone as they are free, and any investment in your time will be easily rewarded with an understanding in increasingly relevant present-future topics.