US National Archives
Nara: American Originals: 54th Regiment Casualty List
An interesting webpage in that it contains a brief summary of the history of the Regiment as well as the Casualty List from the assault on Fort Wagner and two historic photos.
Other
Hall of Black Achievement: Sergeant William H. Carney, c.m.h.: Civil War Hero
A brief biography of William H. Carney, inspiration of the 54th Massachusetts. There is a link to an audio reading of the narrative.
Other
Mr. Lincoln and Freedom: Black Soldiers: Louisiana and Massachusetts
A complete discourse on the incorporation of black soldiers into the Union Army during the Civil War. The 54th Massachusetts Regiment is discussed in regard to the recruitment and the attack on Fort Wagner.
Wikimedia
Wikipedia: William Harvey Carney
This site from Wikipedia contains a biography of William H. Carney (1842-1908), the man who saved the flag during the battle at Fort Wagner. Links are provided throughout for additional information on related subjects.
Other
Historynet: William H. Carney: 54h Massachusetts Soldier
A dramatic summary of Carney's heroic actions during the Battle of Fort Wagner as well as a brief recount of his life following the Civil War.