As a Security Response Liaison, I’m often asked for links to specific information that's available on our public website. Here is a simple list of the more common pages I use for reference.
 

File-Based Protection (Traditional Antivirus) – more info

• Certified Definitions – Download via Http
  Detailed info on what detections have been added - Detections Added (Certified)
• Rapid Release Definitions - Download via Http or Download via FTP
  Detailed info on what detections have been added - Detections Added (Rapid Release)

Firewall and Network Protection –  more info

• Detailed info on what detections have been added – Security Updates
  Attack Signatures for Network Protection

Application and Device Control Policies – more info

• Pre-made policies – Security Updates

Additional Research:

• Symantec Glossary – Fairly complete list of security terms as Symantec uses them.
• Norton Safeweb – See if a specific URL or Domain is known to have malicious content.
• Security Response Blog – Security Response research blog
• Product End of Life Schedule – When each product is set to be E.O.L.
• Internet Security Threat report - Overview of the years threat activity, with quarterly updates.
• Security Response Whitepapers - White papers on a range of issues relating to internet security

What pages do you find are the most helpful?