How can I resize a Mac OS X app window after disconnecting from an external monitor? I'm a MacBook user, and when I'm home I plug into a large external monitor to get additional screen space. When I'm on the go I disconnect and use my laptop's built-in display. For the most part this arrangement works very well; however, I occasionally run into an issue where I'll resize an app on the external, causing it to be too large to fit on the built-in screen when I disconnect.

Most apps don't have a problem decreasing their height automatically or resizing to fit when I click the green orb, but some (like iTunes) don't want to cooperate. How can I resize apps like iTunes without reconnecting to my external?

Here's a screenshot:
Hold down the option key while clicking on the green button.  This should prevent iTunes from changing to the mini-player, and will resize the window as expected.