/etc/ - things that don't seem to fit in anywhere else
What is a session? is it the same as a Cookie? Why do we need them anyway?
Many people are reluctant login to a site that does not use SSL yet they would happily use FTP to transfer their data but is FTP secure?
Perl does not have built in UID generation mechanism, or does it?
The webserver log file is not just about hits and pageviews, it contains lots of usefull information. Most you can comb through it to discover usage patterns
Does your compiler complain about a missing krb5.h even when you have kerberos installed correctly on your system?
Check this page regularly for updates, there are lots of new articles in the pipeline.