Achieve the Core has suggestions for text sets for various disciplines.
Scroll through Louisiana Believes to find great text and ideas for your content area.
TEXT SET IDEAS FROM TEACHERS COLLEGE FOR ARGUMENT
MORE FROM TEACHERS COLLEGE: Sites for text sets and high quality nonfiction
AND HERE'S ONE MORE FROM TEACHERS COLLEGE: RESOURCES
Jim Burke's list of Resources for Images
How about playing with images from Information is Beautiful?
40 excellent short stories for middle schoolers: from Mrs. Waters' blog.
Don't forget to check out Library of Congress: Primary Sources