I end up with all kinds of leftover scraps of scrapbooking paper. This is a fun way of using it up and being creative in a painless sort of way. I don't even follow this "formal" way of going about it. i usually just grab a piece of cardstock or other sturdy background and randomly place scraps on it as they occur. Over time, I'm usually surprised to see a pretty cool "look" emerging. Then it's fun to use it as a background for collage or in the ways suggested in this article.
I also like to do this with paint. When I've used a few colors on a project, I hate to just wash away the leftover paint on my craft palette so I use it to paint swirlies and stars and circles and random shapes on a sturdy paper. Sometimes I just press the paper right onto the palette and lift and let dry. I really like to cut these into squares for Artist Trading Cards. They are great for backgrounds.