One blogger has taken some well known children's classics and created what their covers might look like if these books were not meant for children, but for a serious adult audience.
1. The Fantastic Mr. Fox - Roald Dahl
2. What do People do All Day? - Richard Scarry
3. Lost and Found - Oliver Jeffries
4. The Borrowers - Mary Norton
5. The Wind in the Willows - Kenneth Grahame
6. The Snowy Day - Ezra Jack Keats
7. Peter Rabbit - Beatrice Potter
8. Charlotte's Web - E.B. White
9. Madeline - Ludwig Bemelmans
10. Goodnight Moon - Margaret Wise Brown
I'd be interested to read actual remakes such as these--deepening the morals and themes of these children's books to suit an adult novel would be an interested experiment for any writer, I think.