While you could stick a door on your entertainment centre to hide your cables and accessories, architect Dan Herchenroether shows us how to hide them behind a wall-mounted TV, inside a secret compartment.
Home improvement blog Apartment Therapy has some neat pictures of the setup, and though there aren't any specific directions, the hack doesn't look too complicated. You'll probably have to dig into your wall for this (so be sure you want to do it!), but after that it's just a matter of mounting your TV on a panel, then connecting that to the wall with some hinges. Note that you'll probably want an IR repeater so you can still control the devices hidden within the panel — you don't want to go open it up every time you want to change the channel or turn up the volume. Hit the link for more photos.
A Hidden Compartment Behind the TV [Apartment Therapy]