Typography

What once was a simple selection of letter forms to be organized into words and sentences and then printed, now is the art and technique of arranging type, type design, and modifying type glyphs.
Typography has evolved as both a science and art for one main purpose: to make words easier to understand and more meaningful to read.

Typography is also what you get when you use word cloud generators mentioned in my post Web tools for making word clouds.

Example of typography (click to enlarge):

An awesome example of creative typography

Further reading on typography:
http://free-web-design.co.cc/the-art-of-modern-typography-design.html
http://sixrevisions.com/design-showcase-inspiration/30-creative-typography-art/