In my powder bath, the walls (and ceiling) are silver leafed. It's a strong look, but I like it. It shimmers, and changes colours from cool to warm depending on the lighting in there.
You can see how with this light on it almost looks gold! I think it's fun to go all-out in a powder bath. That is the perfect place to do something extravagant.
While I was at Quatrine in Dallas, one of my favourite stores and sources for slip-covered furniture, I noticed they have a wall that is also silver leafed.
When I looked closer I noticed it's not truly leafed, but it is a wall-paper that is made to look like it is leafed. It is a great look and a great effect. And a lot easier to install than the individual sheets necessary to use for a real leaf-treatment!
Speaking of silver-leaf, I used gold leaf on the dome in this dining room a few years back. Talk about glowing! I wish I had a picture looking up into it. It was one of my favourite things I've done.
If gold and silver are too dressy for you, why not cover your walls in magazine covers? This is a bathroom "papered" in The New Yorker. I think it's kind of tongue and cheek-- magazines are always in the bathroom to read, but this one is all over the walls instead. And it's a great DIY project, no? (image: Photograph by: John Spragg for The Ultimate Interior Designer by Ruth Pretty/Cassell Books)
In the same room at Quatrine that the silver-leafed wallpaper hangs, is a small wall covered in individual maps. I LOVE this look. So interesting, and also another easy DIY.
If you don't want the permanency of gluing maps directly on your wall, here is another display in the same room at Quatrine of maps (of Paris) that cover a wall, but each one is somewhat individually framed and hung as one piece. It's huge and such a statement.
If you've done something like this yourself, I'd love to hear about it. I'm always looking for new ideas!