I ordered An Awesome Book by Dallas Clayton for Luke after reading about it on Design Mom, and I really like it. It has a sweet message, great illustrations, and is kind of quirky. (Note: My sister thinks it's weird. Luckily, you can read the whole book online by clicking here, so you can decide for yourself before you buy it.)
I think it makes a great gift. Clayton self-published the book (but don't worry--it's high quality), so you can only buy it on his Web site. There's little risk of buying a book that the little person in your life already has.