Here are the websites and grief experts and writers that I have personally found to be the most useful.
The thing to keep in mind is that grief is very individual...unique to each person, so there is no "One Size Fits All" or even most.
David Kessler: www.grief.com - compassionate, inclusive, well organized and definitely not about 'fixing' grievers, lots of resources.
Megan DeVine: www.refugeingrief.com - great early grief support, offers a writing program with prompts and has an immediate "I am Grieving" and "I know someone Grieving" info on the landing page.
What's Your Grief: www.whatsyourgrief.com - courses, resource and articles with a solid landing page.
Claire Bidwell Smith: www.clairebidwellsmith.com - author and grief therapist
Hope Edelman: www.hopeedelman.com - author of "Motherless Daughters" and "The After Grief" both solid books on grieving over a long arc of time
Sarah Nannen: www.sarahnannen.com - author of Grief Unveiled: A Widow's Guide to Navigating Your Journey in Life After Loss
Please share in the comments if you have other websites/experts that have been helpful for you.