Melissa Sweet book activities at http://melissasweet.net/
Activity kits for: Ballons Over Broadway, A River of Words, Carmine: A Little More Red, The Boy Who Drew Words, and play games such as Concentration, etc.
Michael Buckley–discussion guide to the first three books in The Sisters Grimm series. http://sistersgrimm.com/pdfs/Grimmguide.pdf
The Polar Express webpage with a calendar of activities http://www.polarexpress.com/calendar/