Nintendo showed why they were top banana after Universal Studios tried to sue them for Donkey Kong. Nintendo tried to be reasonable and offered partnership. Universal refused, hoping to destroy the video game company. At a formal dinner where Universal expected Nintendo to agree to pay profits from their game they were slapped with the truth: the story King Kong is actually public domainnote Something that's copyrights have expired, e.g. Shakespeare, and Nintendo were now taking Universal to court.
E3 2010. While Microsoft was going gaga over the Kinect, and Sony showed little of note (except perhaps Playstation Move), when Nintendo's press conference came, and the public was expecting waggling and casual games, Nintendo instead announced (and showed of) AAA-title upon AAA-title upon AAA-title, and topped it off with the announcement of the Nintendo 3DS! Sure, some of those games are kinda base breaking today, and the 3DS got hampered a bit by some unpleasant news, but at that time it was nothing less than awesome and proved to us why Nintendo was still in this industry! Saying that the fandom rejoiced is an understatement. Summed up here. (Slightly NSFW)
All of this is made even more impressive by Nintendo being the only company there that didn't use a traditional press conference. In true Nintendo fashion, they took their own path, and boy did they succeed.