I get a lot of scratch paper as part of my job entails troubleshooting printers (kill me) and so I have stacks of printer test pages, pages printed out with PCL and PS errors and what not. These make good canvases for sketching up quick network designs or diagraming things such as work flows. I usually scan them in a note taking app before shredding them to keep my desk clear but it’s much more convenient that having to use Visio or something on things that just need to be sketched out