Pure Data

this one is so cool, it gets capital letters on its name.

this is a link to a website containing the download link for pure data. it's music creation software created as a free version by the author of Max, Miller Puckette.

its so much more than that, but you get the idea

serious sound bizness, this one

http://crca.ucsd.edu/~msp/

and this is the link to Miller's book, Theory and Techniques of Electronic Music Production