The Memory Keeper's Daughter by Kim Edwards. Great fiction! Click on the book picture to get to Amazon to buy a copy :).
Jewel by Bret Lott. I read this book in Ukraine when I was pregnant with Polly. I didn't know she had Down syndrome. The book is fiction, about a woman in the backwoods of Mississippi. Her last child was born with Down syndrome. It is a wonderful read.
A friend in the Down syndrome community :). Jennifer Graf Groenberg wrote a beautiful book called Roadmap to Holland. Check it out!