benp -- what color changes in aqua did you want?
Some people with a radically differnt "aqua" were using themes like VGZ mentioned.
Perhaps, however, you just wanted to change the hilight color and the scroll bars from blue to gray and to change the "stoplight" of the close/minimize/maximize window widgets to all gray?
If this is the case, that 's Apple's "Graphite Mode" that can be accessed in the general prefs panel of the system preferences application. Less cool than the themes, for sure, but it takes an edge off of the garishness....
Zach