I've found a few websites that are helpful. I haven't played around with too many of them but I'll try to keep a running list of the ones that I think are of good value.
Centering Corporation & Grief Digest Magazine Online Resources This site has some good information and links, but it also has products that are interesting as well. You can purchase memory books, for instance, as well as books that talk about grief and loss.
Bereaved Parents of the USA This is a non-profit group and they have quite a few chapters around the United States. It's not just for parents, but for grandparents and other caregivers as well. The most helpful things I have found on the site include a list of really good links as well as an article describing some of the feelings that you may or may not have in the first few days/weeks/months/years.
Baby Steps This site has some "sharing" stories and it's very user-friendly. It's not extremely comprehensive, but their list of "do's and don'ts" is pretty good. And it has a cute little house as its interface.
The COPE Foundation This site is very comprehensive and one of my favorite things is called "The 10 Common Myths about Grief and Children." We forget sometimes that our other children are feeling grief, too. Even though Sam is only 3 he still mentions Toby every day and even sings little songs about him.
Grieving for Babies There are helpful videos on this site and you can also join and become a member to share your experiences with other people in similar situations.
Share There's a lot of stuff on here, but the blog is my favorite. Different people write in it and it's good to get an idea of how other people are coping. Everyone does it differently, but there is still enough of an element of sameness to make you feel like you're normal.
Web Healing There are lots of things to explore here. The articles are good and there is also an active forum, too, with current threads.
The Compassionate Friends Network This is one of the most popular grief sites on the 'net. There are events, newsletters, local chapters, and resources listed. There is also an online community that you can join and interact with other members which you may find beneficial. It's also available in Spanish.
SIDS Center This offers a lot of information related specifically to SIDS. One of the best things is information pertaining to the holidays. I find this interesting because even though we never got to celebrate any holidays with Toby, there will still be an ache that he is not there to celebrate future ones. I was particularly looking forward to Christmas this year, for example.
First Candle This might actually be one of my favorite sites. It is very user-friendly and has a lot of information about SIDS, from autopsy reports to current research.