Phluid is a window manager that emphasizes efficiency, speed, and beauty. It uses rasterman's Imlib2 library as the image/font rendering backend. It also attempts to be flexible and compliant with the ICCCM standard and gets a lot of its inspiration from the enlightenment window manager, but some of the initial code design is based on aewm.
The Virtual Tab Window Manager (VTWM) is a virtual window manager with adjustable graphical complexity. With minimal settings, it is ideal for limited resource situations, using little memory, little CPU time, few colors, and little bandwidth. Fully blown, it supports m4 and regex processing of the resource file, sound effects, user-defined color icons and buttons, and more.
WMI is a lightweight window manager for X11 which attempts to combine the best features of larswm, ion, evilwm, and ratpoison into one window manager. It supports both the conventional way of managing windows in a overlapping manner and the screen-alike way of managing windows in a non-overlapping fashion.