The National Archives has posted a List of records digitized by NARA’s digitization partners on their NARAtions blog.
The actual list is posted in List of NARA Microfilm Publications and Original Records Digitized by Our Digitization Partners This page notes that:
"Our digitization partners, Ancestry.com and Footnote.com, have digitized selected NARA microfilm publications and original records and made them available on their web sites for a fee. Each partner allows free searches of some or all index terms for each title. Access to Ancestry.com and Footnote.com is available free of charge in all NARA Research Rooms, including those in our regional archives and Presidential libraries.
"The list below includes all microfilm publications and original records that have been digitized by the partners as of March 2010. The list will be updated when additional materials are digitized.
"Ancestry.com created digital copies of many of the National Archives microfilm publications prior to entering into a partnership agreement with NARA. These digitized materials are included in the list below.
"Footnote.com posts digitized materials on its web site in increments rather than waiting until the full title is available. Any partially digitized materials will have "In progress" in the status column.
"The list is arranged in alpha-numeric order by NARA microfilm publication number. Original records that have been digitized will have “Original records” listed in the microfilm publication number column. The list can be re-sorted by clicking on any of the column headings. Clicking on the titles in the list will direct you to the web sites of our partners."
The list looks like this:
There are columns for:
* Microfilm Publication Number
* NARA Microform Publication Title
* NARA Record Group
A user can do an Edit > Find to see the items on the list for a specific publication number, publication title, record group, etc. For instance, I did a search for  and found a number of records from The War of 1812.
This is a very helpful list from NARA - it is dated March 2010. I hope that they update this list on a regular basis.
I noted a complaint on Facebook yesterday to the effect that "the National Archives has sold out to the commercial database companies who are hiding government data behind their subscription wall."
My view is that the National Archives made a very smart and cost effective decision to use commercial partners to digitize their content - the commercial companies have the technology, the interest and had an economic incentive to do so, and it is a Win-Win for all parties involved - the Archives, the companies and the researcher. The Archives wins because the records are digitized and made available to the public online, and access to Ancestry.com and Footnote.com is FREE at Archives facilities. The researcher wins because there are many more useful records available for a fairly low price - the retail cost for an Ancestry US membership is about 43 cents a day, and for a Footnote membership it is 22 cents a day.
It's not like a user that cannot afford a membership at Ancestry or Footnote is shut out of the records - they can visit a National Archives branch, a local library or some Family History Centers with subscriptions. It's how we did it before the Internet, only better!