We love you, Phoenix shoppers, and we're giving up our most closely held secret to prove it. In fact, it's not just our secret. Up 'til now, no one has known about The Book at Zinnias at Melrose. But now you do, because we're blabbing. You can thank us later.Here's how it works: At Zinnias — the city's latest and greatest Seventh Avenue antiques and collectibles mall — there's this book that's kept behind the counter. If you're looking for something, say a specific vintage coffee pot or a piece of furniture, you can write it down in the book. The dealers who work there read the book and can add your "must have" to their list of stuff they're looking for.Big deal, right? Lots of antique stores have "want lists." But here's what makes the Zinnias book different: People who are not antique dealers — just everyday shoppers and collectors like you — can also ask to see the secret book, which is kept tucked away under the counter at Zinnias. If they have what you're looking for, they can sell it to you from their private collection, and Zinnias doesn't seem to mind."It's like a very low-fi Craiglist, for collectors," Zinnias owner Michael Robertson confides. Robertson let us look at this ultra-private book and pointed out items that customers had found for other customers. Why, since Zinnias doesn't take a cut from all this goodwill, is this good for business? "We're doing just fine," Robertson says. "So why not let collectors share in the fun?"