Clickview - Don't forget to search Clickview for helpful videos.
Britannica School - Britannica has excellent articles on the 1920s and 1930s. Access from school only.
The United States turns inwards - A good overview of the 1920s and 1930s in America from Scholastic.
Becoming Modern - A great range of primary sources on a wide range of topics to do with 1920s and 1930s America.