I've spent a little too much time on the 1940 census to be honest.
Another problem I have is that I have LOTS of families in a fairly concentrated area. When I'm looking for one person, I'm always finding half a dozen others who are somehow related. What I decided to do was make a spreadsheet in Google docs that I could edit as I found these people. My spreadsheet is fairly simple and was created for me to use regardless of what computer I was on or where I was located.
I can also share this Google document with others or publish the spreadsheet live as is done here. I chose to use Ancestry.com's image links, but those on other sites could be used as well. I could share the link with others who might be interested in the same families. If I was sharing with others who didn't have Ancestry.com, I could link to websites on NARA or other sites.
Hopefully this will save me some time from repeatedly viewing the same places over and over.