Computer artists have, since the invention of the personal computer, reinvented different forms of artistic expression.

Consider the ascii art:

http://www.geocities.com/SoHo/2695/links.htm
http://artpacks.acid.org/
http://www.chris.com/ascii_art_menu.html

Through the World Wide Web artists can publish their work instantly. Here is a list of sites from around November of 1998:

http://www.digitalblasphemy.com/
http://www.bmacleod.com/brycelobby.html
http://www.3dluvr.com/deemon/gallery.htm

To create computer graphics there are a huge number of programs from commercial and noncommercial sources:

The word processor Microsoft Word comes with a set of very simple vector graphics tools that can be used to make simple diagrams to spice up a wikipedia article. See How to draw a diagram with Microsoft Word for a tutorial.