• chown root:staff -R /var/local
• chown www-data:www-data -R /var/www
• chown root:mail -R /var/mail
• chown -R man /var/cache/man
• apt-get --reinstall install `dpkg -S /bin/chmod | cut -f1 -d:`

http://www.slideshare.net/cog/chmod-x-chmod