This just in from Ancestry.com - the Philadelphia Passenger Lists from 1800-1945 are now online and indexed. Ancestry describes the index as follows:
This database is an index to the passenger lists of ships arriving from foreign ports at the port of Philadelphia, Pennsylvania from 1800-1945. In addition, the names found in the index are linked to actual images of the passenger lists, copied from the National Archives and Records Administration (NARA) microfilm M425, rolls 1-108 and microfilm T840, rolls 1-181.
Information contained in the index includes given name, surname, age, gender, ethnicity, nationality or last country of permanent residence, destination, arrival date, port of arrival, port of departure, ship name, and microfilm roll and page number. Other listed information may include the name of a friend or relative whom the individual was going to join or a place of nativity. Many of these items may be used to search the index in the search template above.
It is important to note that the port of departure listed on these passenger lists is not always the original port of departure for these individuals. A ship could make several voyages throughout the year, making several stops along way. Oft times the port of departure found on these lists is the most recent port the ship was located at prior to arriving at the port of Philadelphia. Therefore, if your ancestors immigrated to the United States from Germany, they could be found on a passenger list coming from Liverpool, England (if, in this case, the ship left from Bremen, Germany, then continued on to Liverpool, England, before arriving in Philadelphia).
The microcopies of the passenger lists found at NARA are arranged chronologically by arrival date of vessel. If you do not wish to search this database using the search template, the images may be browsed following the chronological arrangement. To browse the images first select the "Year" in which you would like to search, followed by the "Month," and finally the "Ship Name..
To search the indexes, click here.