IDS (Intrusion Detection System)

• Osiris (not perfect, but better than the rest and sensibly designed)
• AIDE (horrible configuration)
• Tripwire (was commercial only when I evaluated)
• Samhain (horrific compilation and dubious security methods)

CMS (Content Management System)

• Drupal
• Joomla
• DotCMS

Configuration management

• Puppet
• CFEngine
• Bcfg2
• Spacewalk (was Redhat provisioning)