Immigrant Ships Transcribers Guild
Transcriptions of passenger lists done by volunteers. Also has ship descriptions, etc.
The Olive Tree Genealogy
Includes ship passenger lists, info on Palatines, New Netherlands (NY) genealogy, and more. All free
The Statue of Liberty-Ellis Island Foundation
This database provides access to passenger arrival records of about 22 million people whose names appear in the original ship passenger manifests for the Port of New York from 1892-1924.