I've had a lot of people ask about the postcard I used on the brain sandwich post. I bought it at the Missouri History Museum gift shop and scanned it in. Today, I can tell you where that sign was! Turns out it was at Carr Lane and Chouteau, next to Saint Louis University and mere blocks from my office, so I took a picture.
Thanks to BoingBoing for solving the mystery!
This also inspired a series of historical blends over on Francis's blog, South City Hoosier.