The Walt Whitman Archives
http://www.whitmanarchive.org/
A vast collection of Whitman material, including complete editions of Leaves of Grass, personal correspondence, and commentary on Whitman's life and work.
Walt Whitman and the Development of Leaves of Grass
http://www.sc.edu/library/spcoll/amlit/whitman.html
This virtual exhibit chronicles the development of Leaves of Grass from its first publication through the "deathbed" edition.
"Leaves of Grass" Reading
http://www.youtube.com/watch?v=j1y24cKeQs0
This video is a reading with displayed verse of a portion of Leaves of Grass.
Walt Whitman on Poets.org
http://www.poets.org/poet.php/prmPID/126
This site gives a summary of Whitman's life and work as well as resources for studying Whitman.