The Online Passenger Lists Guide has two pages:
Online USA Ship Passenger Lists (previous page) and Online International Passenger Lists (this page)
International Ship Passenger Arrival and Departure Records
Listed Alphabetically by Country
Armenian Immigration Project includes a database of Armenian immigrants to North America through 1930
Australia Passenger Lists at Ancestry (these require payment)...
Canada/USA Border Crossing Records
Passenger Lists to and from Cuba
Denmark Emigration Index, 1868-1908 at Ancestry/free to search with registration
Digital Danish Emigration Archives
See the United Kingdom Section below
The Finnish Institute of Migration Emigrant Register (some searches are fee-based)
Passport lists of the crown prince of Äland, 1863-1916 (SukuHaku); and Passport lists of the Äland registry office, 1882-1902 (SukuHaku)
The Hamburg Passenger Departure Records [on this website]
Information about the Hamburg, Germany passenger departure records -- how to research them online and off. Includes a link to the online Hamburg passenger lists database.
Bremen Passenger Lists 1920-1939 (partial)
While most of the Bremen, Germany passenger departure records were destroyed, a few from 1920-1939 have survived. These have been transcribed by a Bremen genealogical society called Die Maus. Also includes transcriptions of card indexes for Bremen ship lists from 1907-1908 and 1913-1914.
Online German Emigration Indexes and Databases [on this website]
Links to websites that have transcribed German emigration lists on the Internet. Includes a brief discussion of how to find these records offline at the Family History Library.
Passenger Ships from Bremen to New York in 1866 [on this website]
A list of every ship (according to NARA records) that arrived at the port of New York from the German port of Bremen in 1866. Included are links to some transcribed passenger lists.
A Ship Missed by Germans to America [on this website]
Passenger list for the Bark Geestemünde, which sailed from Bremen to New York in 1866. Included is a link to the website of the great great grandson of the ship's captain.
Also see: Germans to America [on this website]
Irish Famine Immigrants to New York 1846-1851 [on this website] information about the books and online databases
Watson House - Irish Mission for Immigrant Girls in New York City has searchable records for the Irish Mission for Immigrant Girls in New York City. The records currently online are for 1897-1940 with some years and months missing.
Ships Sailing from Galway to New York (1846-1851) and from Ireland to New Castle, DE (1830-1841) some include passenger lists
Irish Convicts to New South Wales, Australia 1791-1825
Assorted Irish Ships to the US 1803-1804, 1811 from Ulster Ancestry
The Transatlantic Passenger Lists of the Calitrani Immigrants
Calitri is in Southern Italy -- this website lists the ship passengers who came from this region to the US from the 1880s to the 1930s.
Also see: Italians to America 1855-1900 and 1880-1904 [on this website]
from the Netherlands
Holland-America Line Passenger Lists, 1900-1969 [on this website] Where to find passenger departure records for the port of Rotterdam.
SS Rotterdam Ship Passenger List, 1887 (Holland-America Line) [on this website] Transcription of the ship passenger list for the SS Rotterdam that arrived in New York from Rotterdam on May 26, 1887.
Digital Resources Netherlands and Belgium
This site is mostly in Dutch, but it contains hundreds of Internet links to passenger lists for Dutch ships that sailed to the USA and other locations. The focus is on Dutch and Belgian passengers.
Assorted Holland-America Line Passenger Lists
This webpage has a listing of various Holland-America Line passenger lists from 1878-1969 with information about how to obtain them -- some with weblinks, others offline.
Emigration from the Island Texel 1850 to 1920
Includes emigrants to the United States, Australia & South Africa
to/from New Zealand
New Zealand, Archives New Zealand, Passenger Lists, 1839-1973 from FamilySearch
New Zealand Passenger Lists 1800-1900 a collection of over 2000 searchable ship passenger lists to New Zealand
Auckland Area Passenger Arrivals 1838-1889
New Zealand Bound directory of passenger lists
National Archives of Norway has many online databases, including emigration lists and census records.
Passenger Lists and Emigrant Ships from Norway Heritage
See: Russians to America 1834-1897 [on this website]
Highlands & Islands Emigration Society Passenger Lists 1852-1857 Emigrants from Western Scotland to Australia
Scottish Emigration Database contains 21,000 passengers who embarked from Scottish ports 1890-1960
to South Africa
South Africa, Natal, Passenger Lists, 1860-1911 from FamilySearch
Passengers Arriving in South African Ports ongoing project from the Genealogical Society of South Africa
Assorted South Africa Passenger Lists
Ship's Passenger Lists Hamburg to South Africa 1858-1883
Also see the UK section below (for ships that traveled to/from the UK and South Africa)
Passengers to Puerto Rico 1567-1577
Sweden Passenger and Emigration Records at Ancestry...
to/from the United Kingdom and Ireland
UK and Ireland Outward Passenger Lists, 1890-1960 (at Ancestry.com/requires payment); Passenger lists for ships leaving the United Kingdom for destinations outside of Europe. Includes some departure ports in Ireland and Northern Ireland. Outgoing passenger lists prior to 1890 have not survived.
UK and Ireland Incoming Passenger Lists, 1878-1960 (at Ancestry.com/requires payment) Indexes the Board of Trade's passenger lists of ships arriving in the United Kingdom and Ireland from foreign ports outside of Europe and the Mediterranean from 1878-1888 and 1890-1960. The 1878-1888 period is incomplete.
to the United States
See: Online USA Ship Passenger Lists
Uruguay, Passenger Lists, 1888-1980 at FamilySearch