A while ago, I bought a huge spiral-bound sketchbook (it's 11 x 14 inches). There's nothing special about it, although it does have sturdy covers, an elastic closure, and fairly heavy paper. I never planned to actually sketch in it - I am using it instead as my scrapbook journal.
A scrapbook journal is a place for all those bits and pieces of paper that you accumulate: clippings from magazines, old greeting cards, old calendar pages, small drawings and doodles, and all sorts of odds and ends and paper scraps. Some of these things I use in collages, but others I like just as they are and I don't want to see them cut up, painted on, or otherwise altered. So I came up with the idea of a scrapbook journal. It is something like a commonplace book, but for images rather than for words.