SF Signal has created a nifty infographic detailing some of the more interesting moments and concepts in the history of SF's most prestigious and long-lasting award.
I must note that my personal bugbear, the Dramatic Presentation category, is one of the oldest, dating back to 1958. I still hates it, and my argument is not based on its venerability, but on its tangential relationship to the actual fields of SFF and its fandom.