Some visual illusions depend on some eye movement so wander around this for a psychedelic experience. This reminds me of peripheral drift illusions but I'm not sure it satisfies the current explanation for those.
The Bezold effect is named after Wilhelm von Bezold, a German professor of meteorology. It is an optical illusion that makes colors look different depending on their relation to adjacent colors. It works with small sections of color while the opposite effect happens when contrasting large areas of color. In the example you can see that the red lines appear darker when placed next to the black lines and lighter when they are placed next to the white lines.
Another famous illusion, this one was recently rediscovered in a cafe wall at the bottom of St. Michael’s Hill. Although the lines appear to be diverging from one another they are in fact quite parallel.