Variable width fonts from the Linux Font Project.

You'll have to add /usr/X11R6/lib/X11/fonts/lfpfonts-var
to your X font path by either:

$ xset fp+ /usr/X11R6/lib/X11/fonts/lfpfonts-var
$ xset fp rehash

or by adding it to your X-server configuration file (usually
/etc/XF86Config, /etc/X11/XF86Config or /etc/Xaccel.ini) and
restarting the X-server.

WWW: http://dreamer.nitro.dk/linux/lfp/lfpfonts-var.html