We needed a bit of color in my boys' room, so this is what I came up with. Very easy and very cheap. You can buy wood frames like these at Ikea for just a few dollars each. I painted mine white, then found 12"x12" scrapbook paper that went with the room. Glued the paper on, put pictures in the middle, and there you have it! And if you need to cover more wall space, simply use 6 frames, or even 9 to cover the area.
Get creative and give it a try!