ancestorsonboard.com

Taken directly from the ancestorsonboard.com website:

Passenger lists with over 24 million records from ships sailing to destinations worldwide.

Findmypast.com, in association with The National Archives, is proud to present
ancestorsonboard, a new database featuring BT27 Outward Passenger Lists for long-distance voyages leaving the British Isles from 1960 right back to 1890.

With ancestorsonboard, you can search for passenger list records of individuals or groups of people leaving for destinations including Australia, Canada, India, New Zealand, South Africa and USA featuring ports such as Boston, Philadelphia and New York. Passengers include not only immigrants and emigrants, but also businessmen, diplomats and tourists. Images of the passenger lists are available to download, view, save and print."

You may also sign up for their RSS feed of Live News Updates or register for email updates. Either way, this resource is sure to be a big help to many people researching passenger lists both old and more recent. But, be warned, there are fees involved to view the transcript and/or image involved. Without a subscription, it's 5 units for the transcript and 30 units to view the image.