The problems are valuable, and I enjoyed solving them. I think that you might want to show multiple alternatives for solving the same problem - that's one of the cool things about Ruby.
I would love to find something similar to HTML/CSS. I know that codeschool have an HTML5 one, but unfortunately, I need something more basic :)
They may not be HTML5, and I have not had a chance to browse codeschool's offerings, but I'd be curious to hear how it compares in complexity to Stanford's lectures.