You can now access several immigration databases of great interest on the NARA website (in the Access to Archival Databases section). Included are the following:
Russians to America Passenger Data File, 1834 – 1897 (500,000+ records)
Famine Irish Passenger Record Data File, 1846-1851 (600,000+ records)
Germans to America Passenger Data File, 1850 – 1897 (4,000,000+ records)
Italians to America Passenger Data File, 1855 – 1900 (848,000+ records)
Information provided can include name, age, country of origin, city of last residence, occupation, destination, and manifest ID number (but some info may be unknown for passengers you search for). The manifest date file provides name of ship, port of departure, and arrival date.
Interested? Go here: