If you know me at all, you know that I speak at approximately 15-20 events per year. Sometimes, at small local conferences. Other times, at larger national conferences. And still at other times, I'm lucky enough to be invited to international events.
The reason I do it is much less about marketing or exposure, and much more about sharing my ideas in what I view as the "agile community". Even though I'm a strong introvert, I enjoy getting out there and meeting people. Getting the opportunity to share, debate, network, argue, and simply chat about all things agile (and occasionally other topics ;-)