Important IT security websites

Government:
https://isc.sans.edu/ - "Internet Weather"
http://ics-cert.us-cert.gov/ (A)- Industrial Control Systems Cyber Emergency Response Team
http://www.enisa.europa.eu/ - Europe
https://www.bsi.bund.de/DE/Home/home_node.html - Germany
http://www.melani.admin.ch/ - Switzerland
http://dsd.gov.au/ - Australia (top 4 mitigation strategies)
http://www.nerc.com/Pages/default.aspx - North American Energy Cooperation

Companies / Groups: 
http://www.welivesecurity.com/
http://www.ccc.de/ 
http://www.heise.de/security/
http://www.isssource.com

Conferences:
http://www.defcon.org/
http://events.ccc.de/congress/?language=en
https://www.isss.ch/index.php

Threatcheck:
https://www.virustotal.com/de/