Book excerpt: For millions, the perfect weekend includes curling up with a cup of something warm and an engaging crossword. (After all, the "day of rest" doesn't have to be a mental holiday, too ) Puzzle constructor extraordinaire and national competition whiz Leslie Billig has culled dozens of creatively themed Sunday-sized crosswords here, presenting a range of challenges for every puzzle fan. This outstanding collection of brainteasers is sure to deliver many weekends' worth of fun