1940 USA Census
 

in April - and it will be free :)

http://www.archives.gov/research/census/1940/

From the FAQ's:

Q. Is there a name index to the 1940 Census?

A. No. A name index does not exist for the 1940 Census.


Q. If there is no name index, how can I locate people in the Census?

A. You can locate people by identifying the enumeration district in which they lived in 1940 and then browsing the Census population schedules for that enumeration district. The National Archives has placed copies of the enumeration district maps and descriptions in its Archival Research Catalog. For more information go to How to Start Your 1940 Census Research

I believe ancestry are indexing the records but presumably you will need a sub / credits to view the enumeration district etc.

Apparently findmypast is going to be "one of three leading genealogy organizations, including FamilySearch International, that will quickly publish a searchable, high quality name index to the 1940 US Census after it is released in April 2012". Presumably ancestry is the third one. I don't think findmypast has any US stuff at the moment, do they? Hopefully this is the start of them getting lots more?