OK, so maybe its not a complete secret, but after around 10 years of running WordPress I only just found out about it. Here it is:
Obviously you have to be logged in as admin. This basically gives you access to the wp_options table without having to go to a separate database management app, or do some mysql command line ninja.
Who knew? Its not on a menu, probably to hide it from fat fingers, but hey, I wish I’d known about this earlier. Would have saved me a few hours over the course of my work life.