Comp.windows.x.apps FAQ:
Copylefted Software: Software development page of David Allen, which includes full source code for GTKeyboard, an application written for X using the GTK+ tookit, which allows physically disabled users to easily edit text files.
DDD - Data Display Debugger: A graphical front-end for command-line debuggers such as GDB, DBX, WDB, Ladebug, JDB, XDB, the Perl debugger, or the Python debugger.
Dock App Warehouse: Catalogue of dock-applications for different window managers.
dxpc - the Differential X Protocol Compresser: dxpc is a compressor designed to speed up X11 applications over low-bandwidth links (like dialup PPP connections)
Electric Sheep: A collaborative X screensaver for users with high bandwidth.
GTKeyboard: Site dedicated to distribution and information about GTKeyboard, an X11 application for disabled users.
Internet-Based MPEG Video Audio Player:
ivtools: A suite of free X Window drawing editors for PostScript, TeX, and web graphics production, as well as an embeddable and extendable vector graphic shell.
John's World of XV: Multi-format image viewer with some editing capabilities.
Knews: A threaded newsreader with an X Window interface.
Worker: A filemanager for X-Window. It should run on all POSIX-conforming systems. [Open source, GPL]
x2vnc: An X program that will allow two machines to be controlled from the same keyboard and mouse. One machine must run X Window, the other can run X Window or Microsoft Windows.
XFIG Drawing Program for X Window System: XFIG Drawing program software and related documention, libraries, drawings, and pointers.
XFig, FIG and associated software: Links and information related to XFig and other software which uses the FIG graphics format.
Xmcd - X11/Motif CD Player: CD audio player software for UNIX.
Xmmix - X11/Motif audio mixer: Premium audio mixer application for Linux (also works on other platforms running the 4Front Open Sound System (OSS) driver.
XMX Home Page: An X Protocol Multiplexor
xosview: Displays dynamically-updated small bar charts representing CPU load, memory usage, swap usage, paging, disk activity and interrupts.
xpdf: A viewer for Portable Documentat Format (PDF) files.
XScreenSaver: A screen saver and locker for the X Window system.
xstep-shell: Use the Xstep-3.5.1 library and can be used in Linux shell scripts to ask for user input and to draw GUI's for the X Window system.
XtDesk: An X Window icon manager that runs under Linux and FreeBSD.
xvkbd: A virtual (graphical) keboard for X Window system.
XWho: Shows logins in a LAN, extension of utilities for viewing utmp data (who, finger, rwho).
xxkb: A simple GUI for XKB (X KeyBoard extension) and just sends commands to and accepts events from XKB. [Open source, Artistic license]