The folks at Cephalopodcast have figured out a way to let people know that the mic is on and could they please go the hell away because you’re recording a podcast: an “On Air” sign for your iPod. Just follow his instructions and you won’t have to write it on a sticky and place it on your forehead like our friend, Bernard Black.
And once that’s done, take some masking tape, make “walls” around your desk and bitch at people when they refuse to come through the “door” like a proper person.