I recommend what most are saying here. centralize the wiring, and enclose it in something a little more attractive. That really about the best you can do. Ive seen everything from plastic to cloth so if you look around im sure you can find the right material.
on a side note..
(a) the thickness of the wallboard
(b) your patching / painting skills
you could notch the wallboard and bury the speaker wire in it, then patch, sand and paint. This wont really work for anything outside of the speaker wire as its normally fairly thin.
Keep in mind if your renting, this probably isn't the best option as you will need to repair it when you leave (unless your donating electronics, in which case my address is...).
But be warned, it required patience