National Geographic serves up some good-lookin' nudibranchs:
The photo's by David Doubilet, and the whole gallery's here. Some fun morsels in the accompanying story, too: "A few make their own poisons, but most pilfer from the foods they eat. Species that dine on toxic sponges, for example, alter and store the irritating compounds in their bodies and secrete them from skin cells or glands when disturbed." Neat trick, that.