Sicp is a project mainly written in ..., it's free.
Structure and Interpretation of Computer Programs - excercises
h2. Structure and Interpretation of Computer Programs
My work through the exercises of "the MIT SICP course":http://mitpress.mit.edu/sicp/
Putting it on github just because i put all my programming work on github and it seems to make sense to put it where people can follow my progress if they wish.