If painting your walls is just too banal for you then you might want to take on additional challenges. Here's one idea...
Stripe, stripe, stripe. Painters tape is not just for protecting your window panes. You can use it to create patterns and shapes on any surface.
There are, I am the first to admit, varying reasonable degrees to which to take this approach. Perhaps a door? A table? A smaller wall? Use wider pieces of tape, at greater intervals, and you too can have a great looking surface for the price of a can of paint and a roll of tape.