• Neuroscience Tutorial
  Diana Weedman Molavi, Washington University School of Medicine.  Excellent illustrated guide from first-year medical student course.
• Brain Info
  From the Regional Primate Research Center at the University of Washington - Seattle.  Excellent interactive tutorial on identifying structures of the brain. 

Brain Atlases and Maps

• Allen Brain Atlas
  An interactive, genome-wide image database of gene expression in the mouse brain. Funded by the Allen Institute for Brain Science, in collaboration with Nature magazine.
• Brain Maps
  Brain atlases of mammalian brains, including primate brains.
  
• Vesalius
  Gary Wind.  Detailed anatomic drawings of brain and vascular anatomy.  Also includes circulation quizzes, a tutorial on stroke, and an illustrated guide to carotid endarterectomy.
• Digital Anatomist: Interactive Atlas
  John W. Sundsten, University of Washington.   2-D and 3-D views of the brain from cadaver sections, MRI scans, and computer reconstructions.
• Neuro Anatomy
  John K. Harting, University of Wisconsin Medical School.  Neuro-anatomy guides to spinal cord, brainstem, cerebellum, thalamus.
• The Human Brain: Dissections of the Real Brain
  Terence H. Williams, Nedzad Gluhbegovic, Jean Y. Jew. University of Iowa Virtual Hospital.  Textbook  of high quality photographs of the human brain.  The key is in a separate image at the bottom of each page.
• Scientific Visualization
  Arthur W. Toga, Emily M. Santori, Ron Hazani, Karen Ambach, UCLA Laboratory of Neuro Imaging.  Too many sets of images to list here. Includes high resolution images and 3D models.
• Visible Human Viewer
  Syracuse University.  This Java applet allows you to select and view high-resolution images of 2-dimensional slices of a human body, using image data taken from the National Library of Medicine's Visible Human Project.
• Brain Biodiversity Bank
  Fabulous resource with a large database of brain images and the anatomical differences between them. A joint project of Michigan State University, the University of Wisconsin, and the National Museum of Health and Medicine.
• Gray's Anatomy
  From Bartleby.com, this is a great web edition of the 1918 classic by John Gray. 
• Cranial Nerves
  Thackery Gray, Loyola University of Chicago.  Annotated gross images of the cranial nerves.
• Salamon Neuroanatomy and Neurovascular Web-Atlas
  Noriko Salamon, UCLA. Excellent tutorials and quizes in brain anatomy, pathology, and imaging.