Have a look at literate programming (I think that's what it's called). It's not exactly what you're looking for (in that the project must be done that way from the beginning) but you'll find it interesting I think!
That is what it's called. A site [1] with some examples. Donald Knuth developed the term and concept. It seems fairly popular in the haskell community, and to a lesser extent the scheme/racket communities.
Yes, that would be a great place to find more like this. CoffeeScript has added support for literate programming, so that might be a good place to go for modern, web-oriented code samples.
