You can request that we add books to the Library by importing the ISBNs using the Import Books feature. They don't get added to the Library immediately (though that is a feature we plan to add later) but once we have set up more affiliations with other booksellers specializing in older and out-of-print books, we will be adding all the requested books to the Library. When a book you have requested is added it will automatically go onto your Bookshelf.
If a book doesn't have an ISBN, as may be the case with community cookbooks, you cannot yet request it. But another feature we plan to add is the ability to add any cookbook or cooking magazine, whether it has an ISBN or not.