At FLOSS-weekly you can find a collection of 130+ longer interviews with Free Software developers, including some involved in our favourite projects:

#11: Python (Guido van Rossum: “If you give the same task to different programmers, they’ll come up with different solutions. When programmer B at some point has to maintain the code of programmer A, it is tempting to rewrite the code instead, because it would not be the same solution programmer B would have chosen“)
#52: Processing (Ben Fry: “Working in code, changes the type of things I can look at“)
#76: Inkscape (Jon Cruz: “Vector graphics are the shapes themselves“)
#81: OpenStreetmap (Steve Coast: “Maps are never complete. They are always changing” )