DO NOT cut them to the exact length needed to connect them to the receiver. If you do, you may immediately find that you'll need to move the receiver for unknown reasons and at that time, you'll come to the realization that you can't stretch cables.
You may find that dropping the cables next to the receiver's shelf works better- the whole bundle won't be behind the receiver, but you will want to provide some kind of support for the excess, to prevent the weight causing stress to the receiver. Conduit clamps work great for this, as does 1" Velcro straps, screwed to the wall.
Look for lacing bars- they're used in the metal equipment racks that have 19" spacing for the screws that hold the equipment and shelves in place. Securing cables in a rack in an organized manner is called 'lacing the rack' because they used to use string similar to a shoe lace.
http://www.parts-express.com/cat/rack-lacing-bars-and-strips/615