Last, but not least, is the everyman's DIY tool - paint. Most properties permit their tenants to paint the walls, so if you're low on cash but high on creativity, try painting your own headboard on the wall. You can get really creative with the colors, patterns, or shapes you try. A semi-circle is pretty easy to achieve so long as you measure it out right.
Once you've drawn out your shape, carve it out in painter's tape and prime the space inside. Once it's dry, paint on a few coats of your new color. After a few hours, you'll have a bright and cheery addition to your standard bedroom.