5 Fun Apps demonstrates 5 ways to make videos in Second Life -- think tutorials, promotional material etc.
Headtracking is another interesting idea -- it connects to your computers webcam and tracks your head movement then translates that to your avatar. Why? Because it makes the world just a little bit more immersive.
And thinking about immersion, if you've tried voice interaction in SL you might have noticed that the sounds are directional so an avatar to your right will sound like it's to your right. Devil is in the details after all...