One of these ports is San Francisco, which has just had over 900,000 of its images added to www.familysearch.org. The collection, California, San Francisco Passenger Lists, 1893-1953, contains some incredible information for researchers.
Using information I already knew, I searched for Abraham Cohen, who was born in Constantinople, Turkey in 1870. He and his wife and 3 children arrived in San Francisco in the late 1920's. That information quickly led me to the Abraham Cohen I was looking for. The image below is the basic information provided at FamilySearch.
After verifying that this was the person I wanted, I was then able to look at the original passenger list by clicking on the view Image button on the lower right side. That image, shown below, gives great information on the family, and shows that they left Shanghai, China on 10 July 1929.
This collection is very easy to use and as always with FamilySearch is free of charge.