See David Wheeler's page, The Most Important Software Innovations <http://www.dwheeler.com/innovation/innovation.html> http://www.dwheeler.com/innovation/innova

See David Wheeler's page, The Most Important Software Innovations <http://www.dwheeler.com/innovation/innovation.html> http://www.dwheeler.com/innovation/innovation.html>. The page has been online and refined for 12 years. It lists things such as the Stack, Packet-Switching Networks, Spelling Checker, Relational Model and Algebra (SQL), and quite a few other useful and important software innovations.