Ancestry.com has recently expanded its list of free databases. These always-free databases are available without a subscription or free trial. A few days ago, there were slightly over 400 free databases listed in the Ancestry card catalog, and today there are now almost 3000 which include many international titles. The additional databases that Ancestry has opened may only be available for a very short time.
UPDATE 11/1: The additional free databases have already been closed, but the rest of this article still applies for finding the 400 or so always-free databases.
To find the Ancestry free databases, go to Ancestry’s card catalog (which can be found as a drop-down choice on the "Search" bar), and enter the word free into the keyword box located in the left hand column.
As you scroll down the page, you can filter the free databases by collection, by date, by location, and by language in the left column. I found that once I filtered by location, I got a list of all free and fee-based Ancestry databases, and had to enter the keyword free again.
On the green bar, there is also a sort available. By sorting the list of free ancestry databases by date added or date updated, you can make sure are haven't missed any of the newly added or newly opened free databases when you next return to the card catalog.
Sometimes only the index is free and not the image, but info from the image has been transcribed and is available to view for free. Sometimes, both the image and index are available for free.
You will be asked to register at Ancestry.com to view the free databases, but the account is free. Here is a list of some of the more popular free Ancestry databases.