The Library and Archives of Canada has just announced a new online resource, Immigrants to Canada (1803-1865). According to the site:

In 1803, the British Parliament enacted legislation to regulate vessels carrying emigrants to North America. The master of the vessel was required to prepare a list of passengers. Unfortunately, few such lists have survived and therefore, there are no comprehensive nominal lists of immigrants arriving in Canada before 1865.

Some lists have been identified and indexed by name in this database. It also includes other types of records such as declarations of aliens and names of some Irish orphans.

Here is the link.