The 1940 U.S. Federal Census can be viewed if you know where the person lived, if you have an address or enumeration district for that year. If you have no clue where your favorite grandmother lived or where that scandalous cousin lived in 1940 then you'll just have to wait until the indexing is complete so you can search by name.
I registered with Family Search to index records. I was on vacation last week and had intended to work on my genealogy and index the census all week. I had good intentions but didn't follow through. I had a headache most of the week and was nervous about starting the indexing. I am not computer savvy and didn't know what to expect. I finally started indexing last weekend and couldn't believe how easy it was. I can choose which record I want to index and have been choosing New York in the 1940 census because this is the state I live in and where my family was from. The county that I've been getting to index is the Bronx. I would have preferred Ulster county or Brooklyn (Kings county) but don't mind the Bronx too much because Uncle Steve and Aunt Mary lived in that county. In 1930, Uncle Steve was separated from Mary and living with his mother, Teresa (my 2nd great-grandmother). By 1940, Steve and Mary Duper were back together. I hope to find them.
Maybe the genealogy gods will smile down on me and have me indexing members of my own family.