InformationWeek's "The Greatest Software Ever Written" drew on writer Charles Babcock's decades of experience covering software development. Because Charlie judged software breakthroughs "in their historical context," everyone could debate the list and supply alternative candidates. It quickly became our most-read online article to date, and in the days that followed about 300 readers shared their opinions, in an unexpected outpouring of memories. (That rich discussion, alas, was lost in a content management system changeover a couple of years ago.) The Apple Lisa, not the Mac operating system (No. 8), should have been on our list, wrote Michael Bell at Medco. Why not John Kemeny's Basic instead of Java (No. 5)? asked Oscar Shultz at CSC. The Morris worm (No. 12) shouldn't have been on the list at all, said another reader. Babcock laid out clear criteria. He wasn't interested in science projects; the code not only had to be technically brilliant, but it also had to be widespread in the real world. Excel made our list (No. 9), but not Windows or Word. And No. 1? That was BSD Unix, for its impact on the Internet and Linux, and for the philosophy behind it that software "should be a freely available extension of man's intellectual powers -- a force that changes his place in the universe." Software expert Ed Yourdon, author of the Yourdon Report, called our list "a darn good starting point, if not the last word."