When a book wins an award, the result is free publicity for the author and usually additional book sales. The National Book Award is probably the most prestigious, but other book awards exist specifically for self-published or small press books. Most prizes are annual, and there are numerous ones for different categories of books.
Here are some of the book awards you might consider:
Benjamin Franklin Award – PMA IPPY Award – Independent Publisher Foreword Magazine Best Book Awards - USA Book News Writer’s Digest