A lot of the images on here, including the zoomable images, can be viewed and downloaded at full resolution from my flickr: Ben's liquid crystal photography on flickr. Please use these images for educational and non-commercial purposes only.
Liquid crystals are a fluid, but have some properties that crystals have. They are structurally ordered, unlike isotropic ('normal') fluids like water. This means they can interact with light to produce patterns like what you see here when you use filters to see what's happening to the direction of the light polarization state (i.e. which direction the light's fields are wiggling). This particular example has a gradient across the cell in the concentration of an asymmetric additive, resulting in the structure changing how much it likes to twist in a spiral. You can't see the spiral itself, only the effect on the light passing through. Since a spiral has a periodic structure that repeats itself, the result is a periodic stripy pattern that you can see here. It's sometimes called a 'finger print' texture.