Sometimes, a widget only looks good at a given aspect ratio (movies, pictures, etc.).
I wrote a small Swing container for this task today, which you can find at my trac installation. There is also a small example program.
Usage boils down to using
parent.add(new AspectRatioContainer(4.0/3.0, widget)).
instead of just
parent.add(widget);
Perhaps this is of use to somebody.