Visual hints to better spot the currently active window?

My workflow involves a lot application windows, mostly terminals. With a very large dual screen setup, I find myself regularly looking for the currently active window. More than often I type in the wrong terminal, or even start typing in a browser window, because I thought the active window was somewhere else.

I could not find a way to change window properties such as opacity and border / title bar colour. My title bars are either light grey (active) or very light grey (inactive). I am looking for hints on how to make it visually more prominent where the currently active window is.

(Note: I am not looking for keyboard shortcuts or anything that requires interaction)

There isn't a lot that's easily customizable about color schemes on OS X. One suggestion is that if you're using the Graphite color scheme, switch to the Blue color scheme. In earlier versions of OS X,there used to be quite a bit of difference between them, and many developers went with the more subdued Graphite scheme, but by Lion, one of the only surviving differences is the traffic-light dots in the upper left corner of a window. In the graphite color scheme, they're all grey, but in the "blue" scheme, they're colored when the window is the active one.

Besides the brighter metal borders of inactive windows, the shadows are a good indicator to distinguish an active window from an inactive window.

Active windows have a much more emphasized shadow.

In order to increase the visual impact I recommend to use a bright, monocolor background. This will create a maximum contrast in the shadow area.