Interesting articles. I am a sucker for sites others have taken the trouble to research and feed to me and I've found yours to be interesting at least and helpful mostly but it might persuade others less easily persuaded to investigate if you were to give a brief outline of what the site contains.
Those were cool. Another way I've seen the impressionistic one done is to take two separate exposures on slide film and then sandwich them in the mount. Ray Guilette (in my old camera club) has done a lot of these with fantastic results. He was even in PopPhoto back in Feb '06 or '07 and had the cover image, I think. Sandwiching slides gives you lots of creative avenues to explore.