A great tip submitted by Nick Brian: transparent windows. An amazing free application that can change the transparency level of any windows (in Cocoa apps) in a simple key combination! The productivity gain is remarkable as you can really quickly see what is happening in the windows under! The app is called Afloat and is a free download here on MacUpdate. Once the app is installed in System preferences, enabled and the app restarted, you can easily change the transparency of a window by clicking "Ctrl-Command-Page down" to increase transparency or "Ctrl-Command-Page up" to decrease. Thanks for the great tip Nick!