So you wanna see Hubert Keller's madeleine's recipe? Or find the best challah recipe? Or compare your meatloaf recipe to 100 others?
My boyfriend just discovered this, and I've been browsing around a little. You can either type in the name of a cookbook into the search box, or type in a recipe and see which books pop up. I've found the latter more useful personally.
For example, I wanted to bake a challah this weekend so I typed in "challah." I immediately noticed a link to "The Bread Baker's Apprentice." The entire cookbooks is scanned in, so once I was there I was able to "flip" around this 400 page book and learn things like "What is the windowpane method?" and "Can I overwork my dough?" Everything including the front and back covers are scanned, so you can read the table of contents, see color photos, and try a few recipes before committing to purchase. This beats my old method of lugging (dirty) cookbooks home from the library.
Having some knowledge of what cookbooks are out there is helpful. I assume that Google is starting by scanning the most popular books; it might therefore be hard to find really obscure or bad/unpopular cookbooks, but knowing what you're looking for never hurts. Knowing that people on this board like "The Bread Maker's Apprentice" saved me the hassle of clicking on ALL the other recipes that popped up.