I've always been interested in fractals, not so much for the drug references as for the beauty in the balance between chaos and order. Fractals are order that grows into chaos, which grows back into order. It all depends on your frame of reference. Some of the images on this page are beautifully detailed, perfectly symmetrical designs. Others have all the serenity and grace of a cloudscape, or the curving rock formations in the desert.
Almost everyone is familiar with the 2D Mandelbrot series. Even if the word "Mandelbrot" doesn't ring a bell, the images have been a part of pop culture since the 70's. Read more about Mandelbrot here.
3D takes it to a new level. The endless calculations designed to emulate an infinite coastline become a structure with an infinite surface. Like the orginal Mandelbrot series, I think the real beauty is in the close-ups rather than trying to view it as a whole. Diversity in the details.
Hubble keeps on sending us ever more incredible views of our universe. This image is of NGC 3603 - a nebula of brilliant blue-white stars in the Milky Way. The blue color is from the oxygen content of the stars as they burn. The red color is the gas and dust in the nebula that the stars are formed from. The radiation from the stars makes the gas glow red. Note the red giant in the upper left-hand corner. 
