GermanRoots: Links to multiple data sites for German Emigration lists, records, and indexes. This site includes extensive resources in Germany and the US such as city directories, newspapers, land records, and military service records.
Jewishgen has information on Jewish immigration but is not limited to that topic. There is an Ellis Island Records search tab.
Steve Morse has a wonderful site with US and Canadian immigration information that will help with your search, includes census information and calendar conversions.