Getting an HDMI signal from one side of the room to the other is difficult, particularly if you live in an apartment. You can run long cables around the room, and risk tripping over them, you can run a long cable through the attic, or under the floor, but most people end up just moving their components over by the TV.
Gefen has produced three new HDMI extenders, which allow you to transmit signals up to 1080p and 5.1 surround (via SPDIF) up to 30 feet. The device will also repeat signals from your IR remote back to your device, so you could potentially put your components in a closet and still be able to control them. Great, right? Too bad the price on this item is $999. For a grand you could redo your TV room and get a new couch.