Sounds like a real neat idea! One comment is that it is real hard setting out to write a tutorial given a specific subject. [Maybe the challenges can be used for this?] It's possible, but difficult. Another way of looking at it is when we find an image we really like, can we encourage the artist to explain the technique? "Gee, that looks just like a White Oak, how did you do that?" Some will participate, some will choose not to. My feeling is that looking over the shoulder of someone like gevidal, clay, or agor for twenty minutes would be better than sleeping with some book for a year. Even the lesser posted artists sometimes hit upon something that I'd really like explained.