Move your entertainment center as close as possible to the power outlet and cable jack. If possible, try to avoid running extension cords completely across the room.
Bundle cords together with a zip tie. If you have lots of slack in a cord, make a loop and tie it off. Or purchase a shorter cord from an electronics store.
Hide wall-mounted TV cords with a plastic cover that attaches to the wall. Choose a color that blends well with the room. Some flat-screen TVs even have wiring that can go inside the wall. However, cords inside the wall make rearranging more troublesome in the future.