For safety, it's not ideal to place a large piece of art or a mirror above the bed, but you could add paint, stencils, or decals.

If art is installed properly, (anchored/z-bars/security hangers) you shouldn't have a problem adding artwork above the headboard. I could see a grouping with a round mirror centered and two small images stacked vertically on each side of the mirror. Hope this helps!

Replace your existing sconces with a more traditional sconce. Bedding is elegant so try to remember this when shopping for new ones.
And add an oval mirror above bed.

Try something large, round and with some gold (to echo the lamps).

I've seen similar beds with a row of same-size pictures above, but the inside two raised and the outside two slightly lower to follow the line of the bed. Have also seen similar framing but with shorter ones in the center and longer ones on the outer edges, tops aligned. But IMO any art would draw attention away from the lines of the bed. Might be better to put a textural wall covering behind the bed instead and let the bed's lines prevail as the focus.

I think ceiling medallions as wall art would be a nice approach to any shape headboard; I would follow the curve of the headboard in placing the medallions. They are very light too, can be painted, etc. Also, it eliminates the worry about a heavy object falling on my head.

Currently above the bed, I have a beautiful picture but the frame is square (very heavy too) - it detracts from the nice curve of my headboard. I'm on a new mission, finding some pretty ceiling medallions.

P.S. Plates would work nicely too, but again can be heavy.

Check out Gary Riggs interiors website. They do alot of layering and offsetting art off center. Art actually tucks behind the breadboard with layers of mirrors and stuff it's a cool look. But they sometimes put too much. You could go more minimal. They are in Dallas if you google o find web address. Totally got me out of the box.

Thanks Everyone for all of the suggestions. I have some research, and now new websites to checkout for ideas.

Wonderful ideas...

what are the demensions of this room and the size of the bed (full or queen)?