Riemer Digital Library a really great military reference library.

 Dictionary of American Naval Fighting Ships

The Institute of Heraldry The Department of the Army institute of Heraldry has a near complete listing and history of most Army units and a lot of other information and art work.

Army Mottoes This MS Excel file lists most U.S. Army Unit Mottoes and Slogans. The information comes from the Department of the Army Institute of Heraldry