Iridium gives all application windows a smooth, uniform theme. I combine this with a 50% grey desktop background to give me a subtle interface that stays out of the way and doesn’t interfere with my colour perception while I’m working. If you are not a fan of Brushed Metal (why would you be?), and miss the uniform look of the Platinum UI, then I recommend giving Iridium a try.
It comes with it’s own installer, and creates a backup copy of the default Aqua theme if you want to restore the “factory” look. I have just installed this new update; everything works perfectly and looks great.