at the last ApacheCon, The Sound of Knowledge was giving special discounts to speakers for videos and audio CDs of their presentations. I ordered both and they came in the mail the other day, so I decided to sit down and watch my two hour presentation in the name of honest critique.
this is probably something every speaker ought to do, but it certainly isn't pretty. while I knew that this particular talk didn't go as well as it had the other times I have given it (due to the time of day, that I wasn't able to play my music while setting up, and other things), I didn't realize that I was, at various times, utterly unintelligible and inarticulate - there were a few times that I know I was speaking, and it most certainly wasn't in a language anybody could claim to understand.
part of the problem was that I was going very fast - I've given that talk before and it generally takes me over 2 hours, but this time I finished 10 minutes early. and I'm sure that the music had something to do with it (something to mention to the next set of planners). at any rate, I saw lots of things I can do to make my speaking better, so I'll have to work on those for next time.
next time you speak, have a friend record you, either on video or just audio. it's very enlightening.