I disagree with some of the commenters...that wall is not too big to cover in glass tiles. It would however be expensive, so it depends on what your budget is. I could see using a multi-colored glass mosaic tile and adding a few shelves into the mix (one long thin one with a shorter thin one above). It would make for a good place to accessorize.

If the sink isn't used much though, you really don't need to go as heavy duty as tile. Paint would suffice. But if you're going for visual, glass tile will certainly give you that.