Paint. Paint the shit out of that room. You look like a cool grey/charcoal kind of guy, go for it. You can paint the whole room for under $30 I'm sure ($50 with rollers/pans/plastics).
I'd move the desk right up against the windows and maybe move the bed on the same wall as the desk is right now.
Send me one of those two guitars and I think you'll be pretty content with everything. :)
It is still better than my room :(
Posters, paintings, things like that would make your walls look less boring. Your walls are too large of an area to not get used for something in that room. You could paint the walls too, that would help.
I would keep the bed on the side it is in the pic, move the desk under the windows, and then do something big on the wall where your desk is now. A large picture/painting, or paint the walls, with something special on that wall.
Use some of that wall space to hang your guitars. Maybe get so e stuff that isn't black and put it on the walls. Oh, and get some interesting sheets and a blanket.