I tried the headphones thing for a long time, but it would usually result in people just coming over and knocking on my desk until I looked at them.
They'd then give a little polite smile and a "Hey, huh, are you busy? Whatcha doin?"
I feel like a jerk literally shutting the lights off (so they think I'm not here), but it does seem to be working (things are getting done, I mean).