NameVirtualHost *:80

<VirtualHost *:80>
  ServerName katja.darktech.org
  DocumentRoot /var/www
  <Directory "/var/www">
    Options +Indexes
    AuthType Basic
    Require valid-user
    AuthBasicProvider file
    AuthUserFile /var/www/.htpasswd
    Order deny,allow
    Satisfy all
    AuthName "Katjas & Bers Server"
  </Directory>
  <Directory "/var/www/squirrelmail">
    php_admin_flag magic_quotes_gpc off
  </Directory>
</VirtualHost>

vs. 

lzas.dtdns.net

<VirtualHost *:80>
  ServerName lzas.dtdns.net
  DocumentRoot /var/www/wiki
  <Directory "/var/www/wiki">
    Allow from all
    Options -Indexes
  </Directory>
</VirtualHost>