I agree with Wayne, get some standard "thin & white" speaker wire and run it along the corners, ceiling, and floor as necessary. What I've used in the past to keep it in place are small brad nails put in right between the two wires in the cable. Of course be very careful not to actually pierce one of the wires, but just go between the insulation. If the nailhead is visible because of some reflected light, a bit of non-gloss paint on the end should fix that.
I find that the monster "navajo white" speaker cable is a pretty good color match for the cheap generic "antique white" paint often used in apartments. I see bestbuy now carries equivalent AR speaker cable for about half the price, which might be a similar color.
The
PartsExpress stuff is a brighter white, and might be a better color match in some cases. It's also braided, which makes it much easier to fit into binding posts without fraying. Of course that also makes it a real pain to get into the RadioShack banana plugs I like (have to unbraid the end), but you can't win them all.
In most cases these types of speaker cables have paintable insulation, so if you've got matching paint, just buy whatever you like and paint the whole thing.
One important thing to keep in mind is that alot of people are just completely oblivious to what's on your walls or ceiling. In my last apartment I had large black surround speakers (JBL S36's) on the white walls, one of which was in the middle of a wall with the wire just going straight up from the floor. I've had people come in there and not even notice the speakers, until they'd notice some surround effect they'd look over to the side perplexed and say "oh, I didn't realize you had surround sound." So even if you think some wire is alittle obvious and not so great looking, most other people won't notice a thing, so don't obsess over it too much.
Hope this helps,
-- Dave