27 Unique Bed Ideas For Kids and Adults. really good list, great site headboard idea for Murphy bed
One of the easiest DIY headboard ideas I've come across are shutters. You simply lean them against the wall. No measuring, no drilling holes. Love this idea for a headboard in the guest room.
Gal took an old door, stripped it down, added & crown molding to frame out top, sanded (a lot!), painted & distressed it. I like the idea of attaching it to the wall w/a french cleat rather than attaching it to the bedrame.