Resources for developing and implementing multiple-layer firewall architecture

What are some good resources (books, Web sites, etc.) to use when developing and implementing multiple-layer firewall architecture?
Firewalls seem to be a hot topic in the last few weeks. There are many approaches in using multiple layer firewalls, and a wealth of material available to help. Below are some books that should be useful.
"Security Architecture: Design, Deployment and Operations" King, Dalton, and Osmanoglu from RSA Press
"Active Defense: A Comprehensive Guide to Network Security" Brenton and Hunt, from Sybex

And while other Web sites are available, let's not forget to run a query on "network architecture" right here on SearchNetworking.com. There are several items under advice along with other articles that will help guide you.