Mozilla and Firefox. When I was shipping the first versions of those two browsers, I can't tell you how many people said "why do we need a new browser when IE 6 is plenty good" and much of that sentiment came from friends in the industry, not even typical consumers who were even less interested. Then we popularized tabbed browsing, integrated search, pop-up blocking, browser extensions, intelligent addressing, and a whole lot more through compelling extensions. That led to 25% market share for the Web platform in about 5 years. Not bad for a few kids doing after hours work as AOL wound down the Netscape operation after settling their civil suit with MS in 2002.