I'm not afraid to speak in public. I actually quite enjoy it. I might suck at it, but no one's ever come up and told me that. In college I used to travel down to Washington DC with a group of students every year to present project work, and as part of the prep we formed a group that would sit in the audience while other students gave presentations, then take notes on how they did and hand them back in anonymously. "Take your hands out of your pockets", "Stop looking at your notes", "Make eye contact more", that sort of thing. "Stop saying Um." The largest group I've done was for a Giga Research conference in San Diego a few years back, where I think I had around 200 people in the room. Not huge by something like JavaOne standards, but not too shabby.
Recently when I was laid off and working with an outsourcing office, I took an MBTI test that came up "introvert." The rep I was working with said, "That surprises me, based on what I've seen I would have thought extrovert for you." I said, "I'm sure you did, but I can tell you why. The only time you've ever communicated with me is when I'm the one doing all the talking, and I'm talking about myself. I have your complete attention, and I'm entirely confident in what I'm telling you. If you stuck me randomly in a crowd at a cocktail party where nobody knew me or cared what I had to say, you'd see a completely different person."
That's what it's like for me at presentations. Assuming that most of the people in the room actually care about what's being presented (remember my post on two kinds of demos?), I'm in my element. You'll have to pull me away from the podium when my time is up. Sure, I realize that there will always be a percentage of people in the room not paying attention, but as long as they're not the majority and I don't feel like I'm talking to the wall, I'm good. I think I even wrote that in my earlier post about finding the people in the audience that are listening to you, and devoting your attention to them instead of wishing the guy in the front row would put away his Blackberry.
The linked article covers a wide range of presentation subjects, including all of the above (know your audience and don't worry about it), as well as details about how to structure your presentation, font size, graphics, and just about every little detail you can imagine. Good stuff. Now I just need an excuse to do more presentations!
P.S. - I'm like that in non-technical situations too, if you get me talking on a subject I'm passionate about :).