We've talked about their wall applications before and we were totally taken with Wallter's set of mobiles. Originally intended for children, we say it's a waste to not share a bit of whimsy with adults:
What about trying some of these powder coated steel mobiles in the bathroom? Our bathroom isn't quite big enough but if you have a nice window they'd be perfect. Each mobile is adjustable so you can slide the pieces up or down to have them more spaced or less spaced. See all the styles on their website.