Footnote is second only to Ancestry.com in the number of NARA publications available on its website. And unlike Ancestry.com, all Footnote.com content is available for free to patrons (that includes you) at a Family History Center near your home.
On the other hand, unlike Ancestry.com, Footnote.com doesn't provide a way to assist the researcher to find a publication using the NARA publication number or the NARA title. Hopefully this is an inadequacy Footnote.com can soon fix.
For the present time, the good folks at Footnote.com provided me a current list of NARA records available on Footnote.com. I'm not certain if the titles shown are the NARA publication titles or the Footnote.com titles. Also, no indication is provided as to the number of NARA microfilm rolls currently included in the Footnote.com publication of the same, so there is no way to compare the roll count to the total number of rolls currently available from NARA.
In the list on this link, I've created hyperlinks for each publication. Click on the NARA publication number to go to Footnote.com's online, digitized copy of that publication. The publications are sorted in publication order. Use your browser's find or search capability to quickly locate a publication number or search for a keyword in the title.
At the bottom of the article in this link are six publications or collections without NARA microfilm publication numbers. Presumably, these are collections that Footnote has digitized directly, saving the time, expense and trouble of going to microfilm before going to digital. If that is the case, then these are records that previously were never visible outside the walls of the National Archives and Footnote.com deserves kudos for going beyond digitizing NARA microfilm.