If you're going to speak at a conference, as I will at the Drupal Dev Days in Dublin, you must read Kate Matsudaira's post "So you want to speak at a conference…". It's chock full of great advice on first getting a speaking slot at a conference and then making the best of this opportunity. I've got years of speaking experience and still learned (or remembered...) some important bits that will help me leave a good impression on my audience.