General Links for Alzheimer’s (The most wide ranging and helpful sites)
The Alzheimer’s Association link Is probably the most complete one you will find on the internet. There are several sections designed to help you learn about the disease, hook up with your local chapter, find respite resources and suggestions on issues ranging from troublesome behaviors to taking care of yourself.
The National Institute on Aging is another site which offers information, about not only dementia but also about health and aging. It lists a multitude of organizations alphabetically that give more information about age-related issues.
The Mayo Clinic is a nationally recognized health care organization, with a broad range of resources and information. Their page on Alzheimer’s and dementia is very thorough and mostly medical in content.
The  mission statement of National Association of Area Agencies on Aging (n4a)  is this: The National Association of Area Agencies on Aging (n4a) is the leading voice on aging issues for Area Agencies on Aging and a champion for Title VI Native American aging programs. Through advocacy, training and technical assistance, we support the national network of 629 AAAs and 246 Title VI programs. In particular they will link you to Area Agencies on Aging that are local and statewide, for all 50 states plus American Samoa, Washington, DC, Guam, Mariana Islands, Palau and the Virgin Islands.

The 36-Hour Day (Johns Hopkins Press)
This book is considered by many to be the care-giver’s bible on caring for someone with dementia. Not only it is informative about the disease but it has suggestions for activities in each of the stages. Also, you will know what to expect at each stage of the disease. It is a sympathetic roadmap of where you are and where you are going in helping someone with dementia.

Coach Broyle’s Playbook for Alzheimer’s Caregivers
Coach Broyle’s book is another roadmap for caregivers. It is organized by stages, with practical tips for managing daily life and care for someone with dementia.

More links for Dementia in general with specific links about Huntington’s, Parkinson’s 
A general link with mostly medical information about dementing illness with further links for varying types.

Lewy-Body Dementia
This site is dedicated to explaining what Lewy-Body dementia is and how it differs from other dementing illness in presentation and treatment options. There is a section for patients and professionals.
The Mayo clinic is a well-known broad health-care organization/hospital. Like their general page on dementing illness, this one is informative, accurate and helpful.
Helpguide is a site in collaboration with Harvard Medical School and Harvard Public Health. The site is an ad-free place to go for information about a range of health issues. It is particularly helpful in alerting caregivers to the hazards of treating loved ones with LBD  with drugs used for psychosis, as those tend to worsen symptoms.
The Alzheimer’s site provides additional information about other dementias. They always point out when symptoms vary from Alzheimer’s and when they don’t and why it is sometimes difficult to sort out the kind of dementing illness afflicting our loved ones. 

Vascular Dementia Links
The second most common cause of dementia after Alzheimer’s and often co-existing with it, Vascular dementia can be difficult to distinguish from Alzheimer’s disease. It also might pre-dispose to Alzheimer’s making the distinctions more difficult. The Alzheimer’s Association site does a good job of trying to sort our the differences.
The as with their general information on dementia and Lewy-Body variant, the site offers up basic and helpful information about vascular dementia. 
In addition to medical information concerning vascular dementia, the link offers more in-depth information about strokes, TIA’s and the vascular diseases that cause this kind of dementia.

The Alzheimer’s Association gives straightforward and helpful advice about how to communicate with your loved one in the early, middle and later stages of dementia. It offers a sympathetic view for both the patient and his/her caregiver, providing suggestions to keep the channels of love and connection open.
This site is one of the best I’ve found for offering understanding and support for caregivers. There is a wealth of information on the site in general and for caregivers in particular (see below under: caregivers). They offer 10 specific suggestions for improving communication with your loved one. 

Learning to Speak Alzheimer’s By Joanne Coste
Joanne Coste’s book was like an epiphany for me. She had the heartbreaking task of caring for her husband’s early onset dementia (he was in his 40s) while raising very young children. Her book lays out in wonderful detail meaningful ways to communicate with our loved ones to enhance their lives and to make ours easier. Her skill, wisdom and intimidate knowledge of the disease are apparent on every page. 

A Caregiver’s Guide to Alzheimer’s Disease:300 Tips for Making Life Easier by Patricia Callone et al.
This guide offers a more outlined approach to information presentation. It is very helpful for that reason. Some people like a chatty format, other like it laid out plainly and simply. This book does that, and more. It is very helpful and very well organized by stages.

Validation Breakthrough;Simple Techniques for Communication with People with Alzheimer’s and Other Dementias by Naomi Feil and Vicki de Klerk-Rubin
Naomi Feil’s book was the first book I read about communicating in the patient’s world. It shows how important and affirming it is to validate the person’s experience because it demonstrates that we are listening and we care. She uses actual cases and demonstrates in a step-by-step way how to use the technique. This is close to Coste’s book in being revelatory for dementia caregiving.

The site is complementary to the site. I find it very caregiver centered. They deal with all the difficult behaviors on a single page (adding some like eating and bathing) after suggesting ways in which to improve communications and to avoid the prickly interactions that can set off a troublesome response.
As with all the other behavior related links (below) from the site, this one gives clear and concise advice for the possible origins of the behavior and numerous suggestions of how to handle it. Ranging from distractions to relaxation techniques and even snacks (a technique which always worked with my mom). The focus is on making your loved one content and free of distress and keeping you safe. 

Book (very short):
Managing Alzheimer’s and Dementia Behaviors: Common Sense Caregiving by Gary Joseph LeBlanc 
I loved this book. It was very informative and particularly about how to handle certain behavioral disruptions: especially sundowning and aggression. He also talked about caregiver frustration. He’s a real advocate for having a loved one wear a special bracelet when they are hospitalized. Great, short book. 

This link lists the hot topics and fact sheets links that pertain to caregiving. Every link they list is work a click and informative.
This links the home page. Don’t be put off by the layout of the page. There are links for new caregivers, for those whose loved ones are veterans, for caring for you and for finding resources in your state and community. This is one of my favorite sites.
This page too has clickable links for finding your local chapter, for message boards, for support groups for your health and for getting additional care training through your local chapter. It is invaluable.