Ubuntu Gutsy by default disables the use of bitmap-only fonts (a.k.a. X core fonts) through the fontconfig system. This means GTK-based applications can't see them and the user is unable to select these fonts through the standard font selection interface.
The system can be configured to allow bitmap fonts by replacing the symlink /etc/fonts/conf.d/70-no-bitmaps.conf with a symlink /etc/fonts.conf.d/70-yes-bitmaps.conf -> ../conf.avail/yes-bitmaps.conf . However doing so enables all bitmap fonts to come through, which can produce an undesired effect when rendering webpages in Firefox, as some bitmap font names may match those specified on a webpage (Helvetica and Times are common examples).
A small amount of fonts.conf magic can be used to selectively allow certain fonts to come through fontconfig, while keeping most inaccessible. To do this, add the following clause to your ~/.fonts.conf:
<selectfont>
<acceptfont>
<pattern>
<patelt name="family"><string>Fixed</string></patelt>
</pattern>
</acceptfont>
</selectfont>
Inside the pattern block, you can specify an arbitrarily complex pattern to describe the fonts that need to be accessible through fontconfig. In this case, the pattern specifies the Fixed font family.