Gizmo Daemon is a program for controlling your computer based on events from input devices. It has built-in support for all Linux input devices, including keyboards with special keys, joysticks, remotes, dials, and more. It lets you control applications, launch programs, change the system volume, switch desktops, and directly control Amarok. It can visualize system events (such as Amarok sound output, CPU usage, etc.) on capable devices (keyboards with LEDs, Griffin PowerMate, etc.). It also features support for LIRC and RF based remote controls, allowing it to have per-application key mappings and configurable sensitivity settings.
powermated is a program for controlling X applications and command line programs, and for monitoring various aspects of your computer with the Griffin PowerMate USB dial. It can update the PowerMate's LED based on different system monitors (such as CPU usage, XMMS/BMP sound output, and system mixer volume). It also has XOSD support for nifty on screen status displays.
Weak review... This is a discussion of X window managers, not how they relate to current desktop systems such as KDE, and GNOME. I personally use Enlightenment, because not only am I an eye candy ...