http://neuron.duke.edu/
Go to this address to obtain a downloadable neuron simulation program. Complete documentation is available.

http://www.nucmed.buffalo.edu/nrlgy1.htm#fdg_normal_brainx31
You can see a PET scan of a normal brain with links to scans demonstrating pathological conditions.

http://www.coa.uky.edu/ADReview
This web page contains a great deal of useful information about Alzheimer's disease with numerous links to other sites pertaining to the topic.

http://uta.marymt.edu/~psychol/brain.html
You can click on the cerebral cortex shown in vivid color.

http://neurosurgery.mgh.harvard.edu/vaschome.htm#AVMs
This site has a lot of text explaining about strokes, aneurysms, and other phenomena related to cerebral circulation. There are many links to other medical centers that contain diagrams and images of angiograms.