BEFORE:
  nilipod:~ root# df -h
  Filesystem            Size  Used Avail Use% Mounted on
  /dev/disk0s1          500M  446M   50M  90% /
  devfs                  17K   17K     0 100% /dev
  /dev/disk0s2           15G   71M   15G   1% /private/var


Now let's create some more space by using the following commands:

  # mkdir /private/var/Fonts
  # cp -Rp /System/Library/Fonts/* /private/var/Fonts/
  # mv /System/Library/Fonts /System/Library/Fonts.backup 
  # ln -s /private/var/Fonts/ /System/Library/Fonts
  # mv /System/Library/Fonts.backup /private/var/Fonts.backup


AFTER:
  Filesystem            Size  Used Avail Use% Mounted on
  /dev/disk0s1          500M  335M  161M  68% /
  devfs                  17K   17K     0 100% /dev
  /dev/disk0s2           15G  294M   15G   2% /private/var