Social Media

The Register – @TheRegister

https://twitter.com/theregister
Twitter profile: Biting the hand that feeds IT. Technology and science news for world+dog. 
Follow us: Science and technology news for the world

Naked Security – @NakedSecurity

https://twitter.com/NakedSecurity
Twitter profile: Award-winning security news, opinion, advice and research from Sophos
Follow for: Security Industry news and views

CREST – @CRESTadvocate

https://twitter.com/crestadvocate
Twitter profile: CREST is the not for profit professional body representing the ethical security testing & cyber incident response industry
Follow for: Industry news and events

LinkedIn

Institute of Information Security Professionals (IISP)

The global professional Institute for those working in the Information Security/Information Assurance field. Affiliate, Associate and Full membership available to individuals and supporting membership available to corporations, LinkedIn Group is now open to security consultants and practitioners interested in IISP not just members.

This is intended to be a group for practitioners so recruitment consultants and other interested parties such as product sales executives may not be eligible to be linked to this group unless they are members of the Institute.
None of the views expressed here necessarily reflect the views of the Institute and are the individual's own.

Type: Professional Group
Members: 2,360
https://www.linkedin.com/groups?gid=124975&trk 

InfoSec Careers (Information Security)

https://www.linkedin.com/groups/1364287/profile

InfoSec Careers is dedicated to connecting Information Security and Cyber professionals interested in a new permanent career opportunity or contracting jobs with specialist recruiters and hiring managers looking for new talent. This is THE LinkedIn Group for Cyber & Information Security Jobs and all those interested in IT Security news from industry.

This group is specifically relevant for those professionals holding CISM, CISA, CREST, BS7799 / ISO27001 Lead Auditor, CISSP, GIAC, PCI QSA, CRISC, CLAS or similar certifications.

Type: Networking Group
Members: 9,120 

Jericho Forum

The Jericho Forum is an international IT security thought-leadership group dedicated to defining ways to deliver effective IT security solutions that will match the increasing business demands for secure IT operations in our open, Internet-driven, globally networked world. 
This Linkedin group only indicates interest - for actual Jericho Forum members see https://www.opengroup.org/jericho/memberCompany.htm.

Type: Professional Group
Members: 1,057
https://www.linkedin.com/groups?home=&gid=47229

SC Magazine UK (Information Security)

https://www.linkedin.com/groups/1833658/profile

This group is open to professionals working in information security and risk management and is affiliated to SC Magazine and SC branded events including conferences. The SC brand provides information and intelligence for professionals working in information and organisational security.

Its followers include FTSE 100 CISOs and CSOs who are relied upon to protect their businesses from the wide-ranging data threats that exist in the world today.

Type: Networking Group
Members: 6,334

SANS Digital Forensics and Incident Response

SANS provides computer forensics training via live classroom training events and online.

The SANS Digital Forensics and Incident Response community offers digital forensics and incident response professionals an opportunity to learn, discuss, and share current developments in the field. It also provides information regarding digital forensics and incident response training, certification, and events.

https://www.facebook.com/sansforensics

Blog

UK Government Security Blog

https://securityprofession.blog.gov.uk/
This blog will bring you updates about what’s happening in the Security Profession across Government

Security Bistro

http://ddosprotectionblog.corero.com/blog/
IT network security and DDoS security news. Email security, cyber security, spear-phising

Krebs on Security

http://krebsonsecurity.com/
In-depth Security news and investigation

TAO Security

http://www.taosecurity.com/
Since 1998 Richard Bejtlich has defended Western interests from advanced digital intruders. Mr. Bejtlich promotes Network Security Monitoring solutions to help global organizations stay in business by detecting and responding to digital threats.

SANS Digital Forensics and Incident Response Blog

http://digital-forensics.sans.org/blog
The SANS Digital Forensics and Incident Response community offers digital forensics and incident response professionals an opportunity to learn, discuss, and share current developments in the field. It also provides information regarding digital forensics and incident response training, certification, and events.

ConCon Blog

http://www.contextis.co.uk/resources/blog/
Contains news and detailed analysis of research projects and recently discovered security vulnerabilities from Context Information Security.