FBUI is a small, fast in-kernel GUI windowing system for Linux that supports overlapping windows and windows on every virtual console. Its core is currently about 50kB large. See "libfbui" for sample programs and API. This project, while fun and challenging to develop, is now defunct in recognition of the security problems that putting a windowing system inside the kernel gives rise to. The code base remains available, however, in case parts of it may prove useful to the public.
xlayout is a terminal-based utility to get and set information about X11 windows and the pointer. It's designed to be easily integrated into bash shell scripts and takes advantage of the X11 protocol to allow it to access remote X11 desktops. With the aid of the libease library, xlayout provides the ability to smoothly ease the windows and pointer into position.