DIY Organizing Ideas for Kids Rooms - DIY Kids Homework Hideaway Wall Desk - Easy Storage Projects for Boy and Girl Room - Step by Step Tutorials to Get Toys, Books, Baby Gear, Games and Clothes Organized - Quick and Cheap Shelving, Tables, Toy Boxes, Closet Tips, Bookcases and Dressers - DIY Projects and Crafts http://diyjoy.com/diy-organizing-ideas-kids-rooms
I like this DIY headboard. Easy to have the board cut to the right size at Home Depot, almost as easy to cover as the kitchen chairs. Wouldn't even have to mount it to the frame, could just mount some D-rings to the back and hang it from the wall on either side of the window like a picture frame.
Adding lots of pillows could really brighten up the brown couch! Love this example! Plus, getting your own fabric and making pillow covers could be cheap and fairly easy! (plus good sewing experience??)