M.M.
One thing I really like and wouldnt necessarily mean you have to paint but add nice color. You could go to a fabric store and find some fabulous fabric with a real fun print or even solids in the colors you want and get some wooden frames and cover the frames with the fabric, these can be really large and different sizes put together on one accent wall.. here is a sample of how it can look but you can put lots of different ones together of different sizes or several of the same size and shape and different colors.. I think it looks really nice and easy to change the colors (no need to worry about painting) just change the fabrics..
http://howaboutorange.blogspot.com/2007/10/how-to-make-fa...