Kevin Hurbanis sent me a link to his "Searching Chicago's 1940 Czech & Slovak Neighborhoods" page this morning and I asked permission to share it. It's meant as a tool for people who will be looking for ancestors in Pilsen and Lawndale, but it's nicely done and I think it has information that's relevant to us all.
Take a look when you get a chance. And if you know of any other 1940 census tools for Chicago, please post a comment and let us know.
Update: I posted on the ChicagoGenealogy Facebook page this morning and a group member reminded me that Stephen Morse has some great tools for census research on his One-Step Webpages. Check those out, too!