I guess most of you should know what SICP is. I took a class where it was used as a textbook (only the first 3 chapters, unfortunately) and loved it.
Most of the syntax-highlighted code fragments can be clicked on and edited. Either click somewhere else after that or press ctrl-enter to re-evaluate the scheme code. There are also some auto-graded exercises which involve writing code, as well as some multiple-choice questions (inspired by coursera)
So far only the first section is up. I don't think I can finish converting the whole of SICP to this format, so any help is much appreciated! I've tried to make the API as short as I can, but still able to run arbitrary code (eg for auto-graders). The main code is in isicp/coding.js and the content is stored in chapter-specific html files. All this is done via client-side javascript. I used biwascheme for the scheme interpreter and codemirror for the editor.