Erin McKean at Gel 2006 from Gel Conference on Vimeo.
Check out this article on the Mashable blog on social media, with the Top 7 Places to Watch Great Minds in Action, which is a rundown of major conferences known for their compelling speakers. The good news: Lots of dynamic women speakers are represented and you have access to plenty of video examples (like Erin McKean, above) as models for your own speaking practice.