"Overlooked" and "under used" are words that are commonly heard in genealogical circles. But they both apply to the Brigham Young University Immigrant Ancestors Project. Here is the explanation of this Project from the website:
The Immigrant Ancestors Project, sponsored by the Center for Family History and Genealogy at Brigham Young University, uses emigration registers to locate information about the birthplaces of immigrants in their native countries, which is not found in the port registers and naturalization documents in the destination countries. Volunteers working with scholars and researchers at Brigham Young University are creating a database of millions of immigrants based on these emigration registers.There is a good search page provided for beginning your investigations.
However, you may fail to notice the link the "Resources." Here is an example of the types of links and resources available.
Just when you think you have looked everywhere, you find something like this website and you might begin to understand that genealogical research is entirely open-ended.