Education.com posted a list of 50 Books Your Child Should Read Before Kindergarten. Pretty good list.
My favorites from the list include, Flat Stanley, Curious George, Green Eggs and Ham (Dr. Seuss rocks!), and of course, Where the Wild Things Are (read the book and wait a few years for the movie).
Missing from the list is one of my all-time favs for kids, The Giving Tree, now available as a 40th Anniversary Edition Book with CD. It's happy and sad and teaches kids something that will stay with them forever.
See the entire list at http://www.education.com and find some good reading ideas for your children.