"making shadows blue"
this falls under colour theory. It shouldn't be a piece of independent knowledge, it should fall within a larger methodological framework concerning colour usage. You don't just pick a hue direction and go thataway to get an interesting result ( well, you can do that, but it's a bit more complicated if you want to master it) it has to be in a general discussion about complementary colours, seye afterimages, negative space, saturation and warmth impressionism etc etc etc
we have a lot of work in the wiki ahead of us.
Leif, I trust you're interested in the theoretical side as well, right? The more the merrier.