I was conned into doing a formal presentation for about 80 people the other day. Normally, I'm quite happy with smaller team or client presentations to half a dozen or a dozen people; the sudden scaleup put me in a mental state where (at least to myself) I sounded like a crazed televangelist. Maybe it wasn't that bad in reality; some people even laughed a little at the flying pig jokes and no mouldy fruit was thrown.
The good news was that almost all of the technology worked perfectly. For example, the normal experience of a tiny projector that sounds like a badly maintained lawnmower was replaced by a huge bright fixed back-projection screen that everyone could see clearly. No hunting around for books to prop the projector up was required. No "where's the remote, Bob?" conversations because I brought my own (I hate just standing behind the lectern). The exception was the sound system: all the microphones seemed to be broken. I'm always a bit loud anyway, so this wasn't a problem.