eSecurity Planet 
A resource for daily information on e-security targeted to IT managers. The site provides users with information from a variety of sources, including experts at security product and services firms, and the consultants who follow the security industry.
Mosaic user authentication tutorial
Surveys the current methods in NCSA Mosaic and NCSA HTTPd for restricting access to documents and provides set-up and use of these methods.
NCSA HTTPd tutorials
Contains links to several tutorials that focus on security-related, CGI and virtual hosting aspects of server set-up.
Yahoo!'s user authentication page
Yahoo!'s directory of user authentication.
RFC 2069
Request for Comments paper on Digest Access Authentication.