Before you start shutting down your computers, a quick plug for this weekend's New York Book Fair, a fundraiser for the Goddard Riverside Community Center. They'll have plenty of new releases, including children's books, on sale for at least half off the cover price, and more than 85 percent of the money collected over Saturday and Sunday will go to support the Goddard Center's programs, which serve more than 16,000 New Yorkers in the Upper West Side and Harlem. So if you're free either afternoon, maybe you can drop by the Center at Columbus and 88th and start your holiday shopping early.