Here's a fun way to start a presentation: Open with a story, but don't finish it until the end of the presentation.
It works best if there's some drama and anticipation built into the story, so the audience gets caught up wondering, "What happens next?"
One of my clients has a great story about being detained at a casino for card counting; the casino thought he was using a computer, which is illegal. His story builds through being taken off the floor by security, waiting for an interminable amount of time after being questioned, with a tough-looking security guard staring him down and thousands of dollars -- all the money in my client's pockets -- sitting on the table between them. Then the door opens, and the casino manager returns...
At this point, he launches into his presentation on how he came to the point of being a professional blackjack player. His story lingers until the very end of the presentation, where he then relieves the audience's burning curiosity by telling the rest of the story.
I use this technique in my presentation on storytelling, where I leave the story of my house fire dangling until the end.
An unfinished story is a fun way to draw the audience into your presentation; just remember that the story has to be inherently dramatic, and that it benefits from lots of descriptive embellishment to bring it to life in the audience's imagination.
What dramatic story can you open with?