Are you doing a spring spruce-up to your place? Or a complete remodel? Either way, I just came across this super cool wallpaper on Nestmaker that would add a touch of whimsy to your decor.
It's called the Collection from a french company, and you can do things like put up a permanent (albeit well designed) stack of magazines on top of your loo. Or just add some cool bold graphics to an empty wall in the kitchen to give it some life.
Or, even if the landlord says no wallpaper, you can still be an armchair designer of your future dream home. :)