In light of recent events I have been trying to make my apache web server more secure, so I turned to google. I found a few really good articles on securing apache and configuring your firewall. Here they are:
http://www.securityfocus.com/infocus/1531
http://www.securityfocus.com/infocus/1694
http://www.linux-firewall-tools.com/...3-4.html#ss4.1
http://www.linuxjournal.com/article.php?sid=4410
The first two are more focused on the security part and I believe are a good read for anyone thinking about setting up an apache web server, I didn't really understand the third one. The last one focuses on setting up apache with php and mysql, not too much about security though.