As a short lived Social Studies teacher, I know I would have found this website very useful in my classroom.
Digital History is a huge site developed by The Chicago Historical Society, The University of Houston, The National Park Service, and other groups dedicated to preserving history. They have enabled their search engine to find primary sources of information. Here is a link to the New York Times reporting on the Dred Scott Case. Primary sources can be tough for students to find on the internet, so this is a great tool for students to have access to very valuable information. Here is another link to the Journal of Christopher Columbus. Students will no longer be able to say they could not find a primary source for their paper. It is a great tool that I can even use in my English classes if I wanted students to watch the video and read the text of Dr. Martin Luther King Jr.'s "I Have a Dream" speech. Simple searches can open a world of possibilities for your class and your students.
An interactive timeline is a great visual tool for students. Links to speeches and other wonderful sources could help make the Social Studies Classroom a more interactive environment for student learning.
Give it a try.