People with nothing in their hands look like they're heading for the cafeteria. People with a newspaper in their hand look like they're heading for the toilet. Above all, make sure you carry loads of stuff home with you at night, thus generating the false impression that you work longer hours than you do. You can send and receive personal e-mail, chat and generally have a blast without doing anything remotely related to work. These aren't exactly the societal benefits that the proponents of the computer revolution would like to talk about but they're not bad either.
Top management can get away with a clean desk.
For the rest of us, it looks like we're not working hard enough. Build huge piles of documents around your workspace. Pile them high and wide. Voice Mail Never answer your phone if you have voice mail. That's no way to live.