Yes, I did describe Openbox as uber-flexible, and that's because it really is uberly flexible.
Out-of-the-box Openbox is very minimalistic, but that also means it is very fast! Uber-fast you might say.
You get the window manager and a right-click menu and that's about it.
Aside from these, the desktop is yours to embellish as you wish.
Obconf is the application included with Openbox to configure the window manager.