On August 26, 1920 the 19th Amendment was ratified giving women the right to vote. The websites listed below celebrate the 90th anniversary of women's suffrage. All of them have an education component useful for teachers.
Library of Congress -- Votes for Women
The collection consists of 167 books, pamphlets and other artifacts documenting the suffrage campaign and a timeline. There is a related unit for teachers: Collection Connection.
Women's Suffrage by Scholastic (for teachers)
This education site includes the History of Women's Suffrage, When did women vote?, and One Woman votes in 1920: Effie Hobby's Story.
The National Archive has an online exhibit, Woman Suffrage and the 19th Amendment. It is part of their Teaching with Documents curriculum.
The Fight for Women's Suffrage by The History Channel has pictures, video, and articles about the topic with "More to Explore" for people and groups, themes, events, and related topics.
Google Images has a great collection of photographs, cartoons, posters and related ephemera from the era.