The newest books in the New York Public Library don't take up any shelf space. They're <A HREF="http://news.zdnet.com/2100-9588_22-5485643.html?tag=zdnn.alert">electronic books -- 3,000 titles' worth</A> -- and the library's 1.8 million cardholders can point and click through the collection, choosing from among best-sellers, nonfiction, romance novels and self-help guides. Patrons borrow them for set periods, downloading them for reading on a computer, a hand-held organizer or other device using free reader software. When they're due, the files are automatically locked out--no matter what hardware they're on--and returned to circulation, eliminating late fees.