Wall decals are a very powerful way to decorate..especially inexpensively. I've used a company www.slickstickswalldecals.com or just try www.slicksticks.com if you like unique stuff check them out.

The retro pac man design and their space rocks are very cool. They also have a really cool captain rocket design which is popular with teens and comic book fans. Check them out!

Those are so cool.  I checked out the website and I'm partial to the animals they have to decorate kids' rooms, even though I don't have kids.  They're such a cool idea.  Thanks for the suggestion about the hardwood flooring.