Atoms, selections, cut buffers, window manager communication, session management, sharing resources, colors.
X implementation for Intel x86-based platforms.
X Window related papers and talks.
Running X Window over WWW.
Official distribution of X11.
List of over 600 technically-oriented X Window sites: X Consortium, Motif, X Advisor magazine, major X technologies, CDE, internationalization, FAQs, on-line technical papers, on-line tutorials, X for PCs and Linux, and general human-computer interaction.
All you need to know to use Unicode/UTF-8 on Unix and Linux systems.
By Keith Packard. Article on current limits and future development of X Windows. [PDF]
How to set up XFree86 for a TV.
A X11-based print system and API which enables X11 applications to use devices like printers, FAX or create documents in formats like PostScript, PDF, PCL.