The Nerd TV interview with Andy Hertzfeld contains another interesting bit. According to Don Knuth, MacPaint was possibly the best program ever written:
I have another anecdote that has to do with Open Source and the Macintosh. In January, 2004, the Computer History Museum had a little presentation about the marketing of the Macintosh with all the original Macintosh marketing team up on the stage. And a large percentage of the rest of the Mac team in the audience. They had a Q&A toward the end and an older guy got up and said he thought MacPaint was probably the best program ever written. Was it possible for him to see the source code? It turns out the person asking the question was Don Knuth - another one of my heroes. He came up to me afterwards.