I was browsing Flickr for inspiration when I came across this gorgeous turquoise room which I knew you would love. It is the work of US based interior designer Lynn-Anne Bruns who runs lakbdesign. Together with her daughter, Caroline, they designed a room which suited the tween-age tomboy. While this room may belong to someone out of our age range I think it is packed full of inspiration when decorating for any child.
My favourite elements are the polar bear wall which was created from oilcloth bought in John Lewis (not sure if it is still available) and the hanging seat which came from Habitat (not currently available but try this one from Ikea as an alternative).
The origami cranes were made by Caroline (this animation shows you how to make your own). The storage cabinet was painted to match the room and backed with wrapping paper to bring a spark of life to what was previously a standard reproduction piece of furniture. The quilt on the bed was a lucky 1930s vintage find.