My son "attended" just such a school for a year to finish out his high school requirements. It's based on the "Great Books" (Plato, Aristotle, Aquinas, Kemp, etc.) and all work is done online using email and standard "netmeeting" software. I wish we had found the course sooner, as he enjoyed it more and was far more challenged than had been the case for many years. Students who complete the full five years of the Great Books curriculum read, discuss, and write about texts which are the equivalent of two years of a college Humanities course. IMHO, online tutorials like these are one of the truly excellent uses of technology in education.
Was it Great Books Academy or classicalfree.org by any chance?