It makes me extremely nervous to speak in front of a group. I pretty much cannot eat for hours before and am totally exhausted afterwards. It's like an out-of-body experience when I am up there too.
Funny, cuz when I was in college I could yell stuff out from the back of the class (I went to a small, informal art school), but put me in front of it...
I do okay in public speaking though, as long as I am very well rehearsed & have a script. I am not very articulate in speaking otherwise, mainly because my thoughts are not naturally organized.
Although, in debate, I always did well even with points brought up that I did not anticipate.