Michael Silver of cnnsi.com said this, "It was Walsh, after all, who not only revolutionized football strategy with the West Coast Offense, but who also created the organizational blueprint for the modern franchise, from the down-to-the-precise-minute daily schedule to the filming of practices and play-installation meetings." The number of coaches who arose from the Walsh lineage is a testament to his greatness.
Also, check this book out: Bill Walsh's Finding the Winning Edge. It is probably the best football coaching book ever written. I understand it is now hard-to-find, but it is worth the price if you can find a copy. Here is the Bill Walsh coaching tree:
More Bill Walsh stuff: Bill Walsh site. Be sure to take the Test.