I have no aptitude for drawing. I think the only person who enjoys my drawing is my two-year-old niece. Even though I am not good at it, sometimes I have to draw a picture for explaining something, or conversely, I have to refer a drawing for understanding something.
Typical example of it is origami (http://www.origami.com/index.html). As you may have experienced before, when we have to describe in words how to make certain origami, we feel it is a really challenging task and usually end up with recognizing that diagrams (or photographs) are the most effective way to explain it. It is easily noticeable that we just cannot ignore the importance of drawing documentation as much as that of general documentation.
Configuration drawings of drum sets are also good examples of drawing documentation. This site contains biography as well as cymbals configuration of Peter Erskine who is one of my favorite drummers. (http://www.zildjian.com/EN-US/artists/artistDetail.ad2?artistID=1120&genreID=2,4) At the upper right side, you can find the drawing of his drum set, and if you click the cymbals, you can even listen to the sound of them! Both nominally and virtually, this is one result of the modern integrated documentation, and I suppose it could be a prototype for the future documentation.