Wow, grim. The battling patterns are particularly choice.

If the tile is in the shower you could hang shower curtains all the way around. If it's not, you could apply better-looking fabric to them with a starch solution.

Sometimes I try to just work with what's there. Play off the colors in the tile. Go retro.

For the brown and green and blue, I could see blue and green solid towels and accessories working well.

with exception to the missing pieces, I sort of like that last type of tile, I think that one will be easily worked with

Depending on the type of tile, could probably have the tiles resurfaced and turn them into any color you want. Miracle Method is one company that does that and I know there are others. You would need your landlord to agree and I can almost guarantee he won't agree if he (or she) has to spend any of the building's money on the upgrade. The best course of action is to get a quote, see if you can afford it, then pitch the idea to the landlord with the added bonus that you pick up the cost.

http://www.miraclemethod.com/index.htm

if the tile or lineolum is on the floor, you can always lay a removable rubber floor over it, like i did:
http://mylittleapartment.blogspot.com/2007/09/use-rubber.html
all for about $100!

You could paint them. We covered awful tiles, kind of like these, with wood panelling and then painted. It is in a bathroom not in daily use though so maybe its not too practical.

get a nice big beautiful shower curtain and bath mat and close your eyes while you're having a shower...

Try putting some blik graphics on it, they come in soo many different shapes, you could even make those mismatched gray tiles into a neat detail framed by the graphics...

take them off one by one and sell them to someone like me, people want those things, believe it or not.