I've to do presentations in front of 30-40 people regularly (few times a month), and occasionally in front of 100s of people every once in a while. The best thing to do is to make it known that you stutter. I cannot stress this enough. I go out of my way to "stutter on purpose " at the beginning of the presentation (esp. while introducing myself), and again if I start getting anxious. This brings down 99% of all my anxiety. Many people disclose their stutter, and this seems to work as well. Again, repeat after me: "It's ok to stutter, and I'll start the presentation by stuttering on purpose". Say this 10 -30 times .. because. otherwise you're gonna talk yourself out of this.