http://www.thinkport.org/middle-school-literacy.html  Literacy resources feature video tutorials and short, self-paced modules on specific concepts in literacy.  

http://www.thinkport.org/high-school-literacy.html  Literacy resources for high school students and teachers.

http://www.pbs.org/marktwain/scrapbook/  A look at some of his books and actual photos of people and place they were based on.  This is the companion website to the 2001 documentary of Twain's life directed by filmmaker Ken Burns. Its coolest features? Interactive versions of the many scrapbooks Twain kept throughout his life.

http://www.literarywonderland.com/wp-content/Websites/mark-twain/ More fun with Mark Twain and his books.

http://www.marktwainproject.org/ This is an archival project of all things Mark Twain.  It has a section of his letters as well as his books.

http://www.thirteen.org/edonline/americanmasters/about.html Hemingway and Cather are compared and explored in this website.

https://www.willacather.org/  This site has a short visit about Willa Cather and a virtual tour of her home.