The goal of the General Applet Interface Library is to give programmers a simple yet powerful applet interface. This library supports wmapplet/dockapps, GNOME 2 panel applets, and ROX panel applets. The applet programmer doesn't have to care about where the applet will be used, since the library handles that. Over 50% of the code in a dockapp and a GNOME 2 Panel applet does only one thing, setting up the applet window. With GAI, this can be reduced to just a few lines of code.
libAfterImage is an image import, storage, manipulation, and output library for X. It features support for antialiased, TrueTypei, and X text, a 128-bit internal graphics engine, in-memory RLE image compression, high quality image scaling/flipping/blending, multipoint linear gradients, superior quality image output on X drawables, and much more.
PLWM (The Pointless Window Manager) is a highly modularised window manager written in Python. It has no configuration files; instead, you combine Python classes to make the perfect window manager for yourself. This is not a window manager for non-programmers. The feature list includes point-to-focus and sloppy-focus, outline move, resizing, deiconifying, views (extremely powerful workspaces), and multihead support. PLWM is controlled completely from the keyboard.
Wimpiggy is a library for writing EWMH-compliant, compositing window managers using Python and GTK+. The goal is to make writing a window manager as easy as writing a PyGTK application. This library can be used to build a trivial, working window manager in only about 40 lines of code.