If you have a large blank wall that you don't know what to do with, consider framing wallpaper! Get some trim molding cut to the proper size at Home Depot and paint it white. This makes for a dramatic (but inexpensive) piece of wall art.
DIY Projects Using Wallpaper: Make your own hanging wall art with a few wallpaper scraps. Roll the top and bottom of the wallpaper over a wooden dowel and attach with glue or staples. Tie a decorative ribbon or cord from the top and its ready to hang.
Made from blank canvases and metal repair tape. DIY: cut metal repair tape and adhere in geometric patterns to the canvases. The silver material stands out against the blue walls. And lots of other blank wall ideas on this link.