I think this is a great idea. In the digital humanities community, a similar site, the Programming Historian has become very successful. So much so, that it's now being translated into Spanish and French.
Something you might want to carry over from them is the beginner, intermediate, advanced distinction. Beginner material, for example, could include granular explanations of the code being used while advanced level tutorials wouldn't need it at all. And of course the same topic could be presented at different levels.
You might want to ask Bill Turkel if he'd be interested in having some content from his Digital Research Methods with Mathematica undergraduate textbook be brought over to your site. It's already open access.
