Very nice idea.
I like the concept of limiting one's palette, and have used it in the past, although not to such a degree. I've painted an entire Imperial Fists Space Marine army without using a single drop of green (and no; I did also not mix yellow with blue).
But I must admit this came from painting a lot of greenskins and Dark Angels Space Marines just before that, so I was sort of sick of green at that point...
On CMON I have seen several moonlit miniatures, which also used a very limited palette of cold blues and greys, which looked amazing. And also an absolutely stunning Marv from Sin City, completely in black and white, with a single splash of bright red.
I've always wanted to give those moonlit minis a try, and I'm contemplating painting a force of Ninja's for Bushido in that way...