DRILLING A TILE
When you want to hang something on ceramic tiles you will need to drill a hole. Regular metal cutting twist bits will not cut through the hard ceramic face, and in fact the ceramic material itself will destroy such a bit. You need to use a bit that has a carbide head. The one on the left in the first photo is rather pointed and is primarily used for holes in glass and tiles. The one on the right is primarily used for concrete and mortar, but will work on ceramic but not on glass.
One trick to making a clean hole in the right place is to put some masking tape over the tiles. First that allows you to mark the hole easily with a pencil. Then the tape itself helps prevent the drill from drifting around before it begins to cut into the tile. Be patient while it works it way through the hard surface. Once the hole has started, it will move much faster. Floor tiles are much harder than wall tiles, so only use the concrete bit for floor tiles and slate.
Of course once the hole is made you can simply put in an anchor to screw on what you want.
REPLACING A TILE
Now what do you do when you need to replace a tile either because it has old holes in it or it has been cracked? It is not too hard to remove the tile, but remove all the grout around the tile first so working on it will not bother its neighbours. The real problem is that you will never find a tile to match the original colour. Even extra tiles from the original job will not be the same colour because one was on the wall and the other was in a box for the last several years.
A Toronto, Ontario company called TilePix can provide you with very unique solutions, including your own photo on one or more tiles, like the one you see in the last photo. I have to tell you that the quality of the image is superb, like a glossy photo, because looking at the TV image above you wouldn't know it. They can even make mosaic murals with a large photo. There are no more excuses for having boring showers.