Rands, what Steven and J. Dobres said!Toastmasters is crucial, also running through the technology (no laptop disasters) before you make the presentation.

Being that I am a geek who interfaces with the public the two things that will help one overcome presentation nausia are 1) friendliness and 2) humor. Although jokes are good especially if you're good at telling them, it can be something as simple and cryptic as flashing a yelling Pants from your laptop screen background onto the projection screen while you are opening up the Powerpoint program. Better yet, make the last slide bacround a tye dye or Hawaiian shirt background with your acnowledgements.