Hamburg Passenger Lists are indexed on Ancestry.com.
Galveston, Texas
Galveston Texas Immigration Database.
Wilhelm Iwan. The old Lutheran Emigration at the Middle of the 19th Century. A partial translation of this book with lists of emigrants can be found at: http://www.archivaria.com/EmigList/. The site also contains a history of Germans in Buffalo, New York.
Chicago, Illinois St. Michael's Catholic Church on Cleveland Avenue. http://www.rootsweb.ancestry.com/~wggerman/databases/stmichel/index.htm. Places of origin of Germans are listed in this database in the christening records of the children.
BYU Immigrant Ancestors Project.
Transoceanic Emigration Forum: http://forum.transoceanic-emigration.net/viewtopic.php?p=649.