Blogging has been around as a valuable social media tool for a while, and the blogosphere only continues to grow. You can start a blog for free and generate an audience fairly easily by announcing it with other social media. Blogs are a great place for lengthier messages than you would post on Twitter or Facebook. You can provide in-depth details about your event and announce sponsors or speakers and talk more about them. You can provide helpful information about ticket sales or parking details. And during the event, you can live blog about the event for people who couldn't attend. Just be sure to provide a link to your blog on your Web site. You can also set it up so that Facebook automatically imports posts to your wall.