I like playing with the henna-like designs.
I found a link to this color test on Suzanne Engler's blog, Transitional Textile Artist. I scored 11 (0 is perfect and the worst is color blind) and was amazed that I did so well, as I don't think I'm very good at distinguishing shades, tints, whatever. It is a fun little experiment to determine how well you see differences in color. There were several groups of 3 in each group that looked the same to me, and I didn't spend much time on them. Now I wish I'd tried a bit harder.