I have a blue 2009 Kawasaki ER-6n and I have recently mounted a Givi v46n top case on the back. Prior to the Givi case I had a $50 JC Whitney case mounted. While the JC Whitney case worked, the Givi case looks much nicer. The case is mounted on an FZ449 Givi rack.
I love having hard luggage on my bike. It is so convenient to always have a place to throw a grocery bag on the way home for work or a safe place to stick your helmet when you need to run an errand.
See also: My Video Opening and closing a Givi case