On a recent trip to Kaua'i, I stayed in a rental home where the headboard was this tropical foliage painted on the wall. It's a fun idea that's affordable, unique, and adaptable to any size bed and wall. You can go with something floral like this, a traditional headboard shape, a simple stripe of color, or whatever else you can imagine. (This is a great place to use those wall stencils, too.) And when the color or design no longer suits your style, just paint over it and start anew!
Here are a few more inspiring faux headboards…
A clean and simple trome l'oeil design featured at Apartment Therapy (photo by Evan Koester)
A clever small-space solution seen at The Stir