Beyond the health hazards of tripping over a mess of wires, it's also an aesthetic problem. Nothing says "disorderly" like a room full of cables running amok. Area rugs and carpets are great hiding places, and the same goes for furniture. If you have a cord that needs to reach across a room, you can run it along (or behind) baseboards and doorjambs. Then paint the cord the same shade as the wall and use wire tacks to keep it in place.