My community site for bass guitarists, Bassplaying.com runs on Drupal, the incredibly good open source CMS. It had been running version 4.6 for quite some time. But that version is no longer supported, so I finally made the jump to 4.7.10, which was fairly painless. I also went with a new theme, called Amadou, which, while it still needs some tweaking, is pretty nice right out of the box.