You don't frequently come across collections of short stories for children, but this one by Oliver Jeffers would be a standout even if you did. Each story is dedicated to a letter of the alphabet, and the characters introduced in one reappear throughout — it's delightfully interconnected. Read them all at once to a child with a longer attention span, or do a few a night with someone who can't sit still for very long.
What kind of reader is it for? Someone who already knows the alphabet, but would like to think about that oft-repeated series of letters in an entirely new way.
Find it here.