The fine art of drawing diagrams using the ASCII character set (mainly |, -, /, \, and +). Also known as character graphics or ASCII graphics; see also boxology. Here is a serious example: [Examples deleted because MT choked on them. To be fixed - PM]
The next step beyond static tableaux in ASCII art is ASCII animation. There are not many large examples of this; perhaps the best known is the ASCII animation of the original Star Wars movie at http://www.asciimation.co.nz/.
There is a newsgroup, alt.ascii-art, devoted to this genre; however, see also warlording.