IMDb
http://www.imdb.com/title/tt0116493/
IMDb page for the 1996 film Harriet the Spy, starring Michelle Trachtenberg as Harriet and Rosie O'Donnell as Ole Golly.
Random House Kids
http://www.randomhousekids.com/brand/harriet-spy/
Random House Kids's website for Harriet the Spy, featuring bonus material such as a page with ideas for hosting a spy party.
Unapologetically Harriet, the Misfit Spy
http://www.npr.org/templates/story/story.php?storyId=87779452
An NPR article about Harriet the Spy, discussing the way it reflected changing children's literature of the 1960s because of Harriet's unconventional behavior.
Louise Fitzhugh is Dead at 46
The New York Times article that announced author Louise Fitzhugh's death, while also discussing the impact that Harriet the Spy, her most famous work, had on children's literature.