I have been to a lot of conferences and seen a lot of presentations from brilliant people, but sometimes those brilliant people fail to make a presentation that connects with the audience. As an audience member (and not speaking as one of the brilliant people presenting) I have just one advice for those speakers.
Speak at conferences because you are on a mission. Don’t give a presentation just because people ask you to, and you are flattered. Make sure to think about what you are giving the audience – what the audience should take away from your talk (and make it simple). At conferences most attendees are on information overload, so you have to inspire them for further investigation. Tell jokes, tell anecdotes, use images to let your audience connect with your material. Be enthusiastic. Be memorable. Be tweetable. Be bloggable. Be the odd one out. Make sure that everyone knows why you are on that stage and what you are talking about.