Check out this article about FLVS also known as Florida Virtual School. This is the program Michelle has used for many of her high school classes, (algebra 1, geometry 1, spanish 1 & 2, biology, chemistry, american government, economics, webmasters, SAT prep). She was able to take these classes, free of charge and retain her homeschool status here in Florida. The teachers were always very helpful, very understanding and very supportive of her being homeschooled.
The only issue I ever had was that they tended to focus on grades more than I would have liked – Michelle was often urged to resubmit assignments for a higher grade if she got less than an A an an assignment. For us, it wasn’t about the grades it was about learning. If she submited a geometry assignment and got a C then what that meant to us was she needed to figure out where she went wrong, work on that and move on – getting a higher grade just wasn’t part of that, or necessary. Teachers were understanding about our decision, she wasn’t pressured to resubmit, they just always assumed she would want to (or that I would want her to).
I don’t think online or virtual schools are for every child, but I think it should be immediately discounted either. Even kids who are in school can use these types of virtual school to explore subjects not available to them or to more deeply explore subjects that they have great interest in.