A recent HarperCollins Children's Books marketing promotion for the August release of Little Lit: It Was a Dark and Silly Night by Art Spiegelman and Françoise Mouly turned out to come in very handy during last month's blackout. Small penlights, which were created to promote the book, were distributed to employees leaving Harper's midtown offices that Thursday afternoon in order to help them make their way through dim hallways and stairwells as well as dark apartments. "In the world of notepads, pens, buttons and window clings," said publicity director Amy Burton, "who would have ever thought that a promotional item could be such a lifesaver!"