Apartment wall art? I have plain cream walls, can't paint, can't put any sort of...

I have plain cream walls, can't paint, can't put any sort of hole (not even tacks) contained by the walls. I've decorated surrounded by green, browns, earthy tones. I have no money for wall decor. I'd approaching large, bright wall art. Please, provide me ideas!
Answers:    Put up personal photography or a friend's photography. You can own the pictures enlarged at Kinko's or some place similar.
Are you sure you aren't allowed to hang pictures? That would be unusual. If explicitly true, the best you can do is buy or have made lightweight folding screen. You can position them behind furniture or use them as dividers. Either cover them near pops of colorful fabric to clash your decor or hang pictures on them.