If you still don't know what Zentangle is, check out zentangle.com for information. I enjoy the relaxation it encourages. This first piece was from a pattern coloring book. The first image is the untouched page.
This is the completed Zentangle done by using the pre-drawn pattern as the string. All of this is done with a .01 disposable technical pen.
This is a bit different. I had a tank top that had gotten dingy and lightly stained. I took a very fine Sharpie pen and did a Zentangle on the shirt for a unique piece of art.