amiwm
An X11 window manager that makes a Unix workstation look and behave like the Amiga's Workbench.
Marcus Comstedt wrote amiwm in the mid-1990s, as plenty of Amiga owners moved to Linux and NetBSD without wanting to give up the interface they knew. It copies Workbench 2.0 and later: frames with the Amiga's depth gadgets, a menu bar that only appears while the right mouse button is held down, and icons sitting directly on the backdrop.
The most Amiga-like part is the screens. As in Intuition, several screens can be stacked and the front one dragged down with the mouse to reveal the one behind it — a take on virtual desktops that no other X window manager really picked up. amiwm is small, has barely changed since the turn of the century, and today is mostly used by people who miss 1992.