To cover my all white walls I collected some pictures that might suit here. To keep this even a bit cohesive I'v tried to stay mainly in black, white and red (Let see how long I can hold this line:))
The center ones are just to cover that dirty unpainted wall. I still havent painted the alcove because I'm planning to highten its floor and built a bed in it. I would also put some color into it.
and I still have some pictures that I don't know where to put yet :D