Skippy is a full screen pager for X11, not entirely unlike expocity and Apple's Expose. It arranges snapshots of all windows on the current desktop, allowing you to easily switch between applications. It doesn't require a specific window manager, but requires NetWM or GNOME WM specs compliance to work.
Skippy is a window management tool for X11 similar to Mac OS X's Exposé feature. It allows a user to quickly see open windows by two different sets of criteria, or to hide all windows and show the desktop without the need to click through many windows to find a specific target.