I saw this artwork by photographer Amanda Weil, in House Beautiful and I thought the idea of a transparent or translucent image printed on glass was intriguing. Old daguerreotypes were printed on glass, so the idea could be adapted for some very steampunk images.
Weil makes furniture and screens as well as wall art, but for the DIY photographer, I'd look into Fracture. You can get an 18 inch diagonal print on glass for $35. According to their FAQ, "You'll be able to select "No Mount" for just the opaque printed glass or "Transparent" for the printed glass without any white background." I think that, paired with a sepia or black and white toned photo, would make for a impressive wall.