Handling nervousness
I have three tricks for handling nervousness:
Prepare like crazy. The more I practice a talk, the less nervous I get. There is no substitute for the confidence attained by practicing your talk in close-to-real conditions a dozen times.
Accept it. Even when I'm extremely prepared and have no fear of disaster, I still get a boost of adrenaline as I take the stage. I've come to expect it, and now embrace it as a bonus--once I complete my talk I still feel high for hours.
Beta-blockers. I've never used these for conference talks, but I have for important singing gigs. Beta-blockers are a kind of miracle drug for handling nerves. They don't sedate you at all, but simply block your body's physical reactions to nervousness, like rapid heartbeat, sweaty palms, shallow breathing, or drymouth. I've never experieneced any side effects, and doctors seem to prescribe them happily. If you have extreme anxiety about an upcoming talk, consider them.