Loganberry Books is a bookstore in Ohio that also sells books online.
Even better, proprietess Harriett offers an amazing service called Stump the Bookseller.
So you know that book you loved as a child, but all you can remember was that it had a girl and a white pony, and the pony's name was snowball or snowdrop or something - and oh yeah, there was a really wicked witch in it?*
Well, you send Harriet $2 via Paypal and a description of the book. She, and various readers who are librarians or teachers, or just book-lovers like me, search and write in with info to help you out. If Harriet finds the book for you she'll get it and you can buy it.
What is most amazing about this site is not the joy when the book is found, but the sheer number of stories people remember from their childhoods. I love that a book can be out of print since 1923 and yet, someone was so touched by an element of the story that they will remember it (and look for it) 50 years later. It is a beautiful testament to the power of stories and how they continue to move and inspire, delight (or creep out) years after you first read or hear them.
* Reading descriptions of books with the keyword "witch" reminded me of the title for the out-of-print (and now quite pricey) The Wickedest Witch in the World which I thought had been lost in my subconscious forever! Author Beverly Nichols was apparently a gentleman.