On the Internet you can find many sites covering information security. All of them are not a relevant study guide for IS professionals, but may include very interesting information. The links listed below are just some of all those links.
(ISC)2 www.isc2.org The starting point for your CISSP examination
CCCURE www.cccure.org The best studyguide for the CISSP examination, with documents and links.
ISACA www.isaca.org Foundation for information security auditors, administers the CISA certification.
CERT Coordination Center www.cert.org A center of Internet security expertise.
Incidents.org www.incidents.org A virtual organization of advanced intrusion detection analysts, forensics experts and incident handlers.
NIST CSRC www.csrc.nist.gov Computer Security Resource Center at NIST .