Love the idea. There are some very knowledgeable people on this forum, that already write great articles (for example, I read through Neuroanatomist's article on autofocus yesterday and thought it was very good). I suspect that that's one of many of his articles. Given some of the information posted on this site, there must be many others already writing great content (or capable of it). It would be great see some of these articles listed on this site.
But playing devil's advocate, chances are that if you are good enough to write tutorials, then you're good enough to get paid for it, or develop your own site and have control over your intellectual property and, if you wanted, generate some income from it via advertising or through promotion of your own business. It would be interesting to see how many people would voluntarily contribute detailed content. But prove me wrong. Don't let my negativity affect things. I think its an excellent idea and worth trying.