Library of simple functions that are optimized for various CPUs.
http://liboil.freedesktop.org/

The Tango Desktop Project exists to create a consistent user experience
http://tango.freedesktop.org

Maps the new names of icons for Tango to the legacy names used by the GNOME and KDE desktops.
http://tango.freedesktop.org/

File manager for Xfce

Settings manager for xfce

High-level API for X Keyboard Extension
http://gswitchit.sourceforge.net

Lists of the country, language, and currency names
http://pkg-isocodes.alioth.debian.org/

A simple calendar application with reminders for Xfce
http://www.xfce.org/projects/orage/

Font family based on the Bitstream Vera Fonts with a wider range of characters
http://dejavu.sourceforge.net/

Xfce window manager, compatible with Gnome, Gnome2, KDE2, and KDE3

Desktop notification library
http://www.galago-project.org/

A session manager for Xfce

Panel for the Xfce desktop environment
http://www.xfce.org/

X11 Composite extension library

Window Navigator Construction Kit

X11 Resource extension library