The power of a message comprised of 140 characters has been proven again and again. Twitter is a great tool to use for event marketing because of how easy it is to track your results. Start by creating a hashtag for your event -- you know, that little # sign followed by a name. Then, start promoting the hashtag: Put it on your Web site, use it in your Facebook posts, print it on the invitation, in the program, on name badges and use it in presentations and slideshows. Be sure to mix up your tweets beyond simply announcing your event. You can use it to announce up-to-the-minute details, like new sponsors or speakers, entertainers or even an open bar. Plan to keep up the tweeting during the event as well.