Three words: Chrome split loom.
But really, any wire install can be improved, even if the wires don't disappear. It's all about planning, but what AtomicLabMonkey said holds true-- bundling your wires together with a few simple zip ties while trying your best to keep the wires taut helps a bunch. I would bunch all the cables together, and run them along the ledge that the TV sits on, and then up the back of the bookcase.
You can also pick some spiral wrap, it can make an install look nicer as well
