For years Ive carried around and touted the idea of having a sketchbook (or blackbook, moleskin, etc). Here's a man who specializes in notebook skecthing, or doodling. Mike Rohde's design, logos and thoughts come in the form of neatly skecthed illustrations, that he keeps organized in his books.
Mike's visual diary includes a whole set of random ideas and drawings, basically anything that inspires him at the time. He held a panel at SXSW on Visual Note-Taking, which can be seen here: