emedicine, part of Medscape (medscape.com), is a terrific resource for physicians. Access if free, though you may have to register for an account. Many of the articles are understandable by lay people. The articles are reviewed by MDs and updated periodically.
I like this overview of the “Parkinson-Plus Syndromes”:
This particular overview includes these sections:
* Clues to Diagnosis
* Multiple System Atrophy
* Progressive Supranuclear Palsy
* Parkinsonism-Dementia-ALS Complex
* Corticobasal Ganglionic Degeneration
* Diffuse Lewy Body Disease
* Management of Parkinson-Plus Syndromes
Of course MSA, PSP, CBGD (now called CBD, short for corticobasal degeneration), and DLBD (more often called Dementia with Lewy Bodies) are part of our local support group.