It's amazing how many programmers have never heard of Grace Hopper. Even I, who have gone around saying things like, "She was the mother of us all!" didn't realize until last year that she wrote the first compiler.

When I wear my Polish-American Girl hat I am always so proud of Marie Skłodowska-Curie. (And extra points for putting in that "ł"!) It always annoyed me that so many people think she was French!