Afloat is a Cocoa plug-in that allows your windows to float above all others (thus the name), make them transparent, and move them without having to go search for the title bar. This last feature is what I use the most. And I was quite amazed when I realized that I can detach and move the drawers of Cocoa windows as well. Watch the screencast for an illustration. That’s quite a useful thing since I can place them now like regular tool palettes.
When checking out Afloat, make sure you fully utilize its key/mouse bindings. While pressing Cmd-Ctrl use the mouse wheel to increase/decrease transparency, or move the mouse to drag the window.