Steven Black's INTLToolkit
Make your Visual FoxPro apps multilingual
INTL's Quality Source Code
"...the source code itself is a treasure. I get to see a lot of source, and Stevens is among the best Ive seen."
Steven Black's INTL Toolkit is a great example of literate programming. It is designed in such a way as to teach you the maximum about itself, and also about FoxPro.
Much of INTL's architecture is named explicitly after the design patterns it emulates. The result is a black box tool that'll easily become a white box in the unlikely event you need to change it to your particular circumstances.