The Lewy Body Dementia Association provides general information about the disease, support information for caregivers, a newsletter, and lots of links.
Hosted by the University of Nottingham (UK), LewyNet provides a lot of information without too much obtuse medical jargon.
Technical Articles/Current Research
A great source of information is the National Library of Medicine. Enter "Lewy body disease" into the search field to find abstracts of published research articles.