What do you put on your desk? Staples. Pencils. Paper. A laptop. What don't you put? A 1:24-scale electric jet engine you built yourself, one so loud it sounds like... uh... a jet engine.
Built with a DC motor from an old hairdryer, the jet engine isn't really an engine, as it doesn't produce any thrust. It is however a rather neat looking fan -- the perfect thing to keep you cool while you type away at your desk.
The biggest problem is the noise. At full throttle, the fan runs at a nippy 3600rpm. So it may prove too distracting to have on all the time.
If you're interested in how it was made, a tutorial of sorts is available, though it's more of an explanation and not a step-by-step guide.