New recently at Ancestry.com: the U.S. Social Security Applications and Claims Index, 1936 – 2007. This is a “companion to” the Social Security Death Index (SSDI) we’re all familiar with. It contains about half as many records as the SSDI, but has some individuals not listed there, since it isn’t just death benefit records. I wasn’t able to find any of my relatives in it, but Ancestry’s Juliana Szucs did. For a detailed discussion please see her July 24 blog post, or this post in the NGS blog.
This is an “index” database, that is, it has transcribed data but not photos of the original records. FamilySearch doesn’t have this data yet, as far as I can tell.