Found this thread on Ask Metafilter yesterday, but it was really hard to read, much less post. It started when a woman asked for advice on how to help her best friend, who'd just lost her 6-month-old daughter. There's some really helpful, thoughtful advice, but be warned: you'll need the tissues ready.
If you can't bring yourself to read it now, fine. Just file it away and hope that you'll never need to know. Otherwise, here the two most salient points to remember:
What can you do when a child dies? [ask.metafilter.com]