The Foundation for Blood Research has created an online course in Evidence-Based Medicine, aimed at "advanced high school science students, college students, nursing students, and 1st or 2nd year medical students." It focuses on evaluating research papers and applying statistics to medical diagnosis. I have taken this course, and it was useful practice in Bayesian reasoning.
The course involves working through a couple case studies of ER patients. Students will observe the patient, review research on relevant diagnostic tests, and calculate posterior probabilities given the available information. For instance: once case involves a woman who may have bacterial meningitis, but her spinal fluid test results are mixed. Students then read parts of a paper describing the success of different components of the spinal fluid test as predictors of meningitis.
The course is self-paced and highly modular, alternating between videos, multiple choice or calculation questions, and short written submissions. There is no in-course interaction between students taking the same course, but it is divided into "class sections" for the convenience of teachers who want to observe their students. It works well with Firefox and Safari, and slightly less well (but still easily usable) with Internet Explorer.
Anyone who is interested or wants more information, look at their website or ask me in the comments. Once a decent number of people have shown some interest, I will contact one of the site administrators and he'll set up an official class section for us.
EDIT: I have contacted the site administrator, we should have a class section available soon. Section name and info on how to log in will be posted shortly.
EDIT2: The course section is up: go to the http://evidenceworksremote.com/courses/ and then find the Less Wrong Community course. When you click on the course listing you will be asked to register. Once you receive the acknowledging email return to the course and enter the "enrollment" key: LW101 . I will be able to see your responses to the questions and possibly able to provide feedback. Once you have completed the course, Dr. Allan, who is one of the developers, would appreciate feedback by email.