I rarely read eWeek, but this caught my eye today:
#14: Keep an eye on the time and let your participants know you're aware there's only 10 minutes left, 5 minutes left, and try to end the event promptly (if not early). If participants get the sense that you're off in your own world, they'll bail on you, without waiting to see if you wrap it up on time.
#15: Build in interaction. To ensure people stay engaged (or wake up once asleep), ask questions, send polls, mix your show-and-tell up a bit.
#16: Be energetic. Find a way that works for you (I often stand up when presenting) to keep your voice energized and engaging.