I love ideas that take something old and rejuvenate it easily and at a low cost. Take an old canvas artwork, prime it, and paint it yourself in colors to match your room (use acrylics or oils). If you don't have a canvas, you can get one relatively inexpensively at most craft and decorating stores. You don't need to be a master artist, just put some colors on it in a way that's interesting and pleasing to the eye. Voila! New look to your room with little to no expense.
See how the Thrifty Decor Chick did it, complete with before and after photos as well as step-by-step instructions.
[Photo courtesy of the Thrifty Decor Chick.]