Comprehensive
A friend and co-worker of mine, Mr. Martin Brown, is in the process of putting togeather one of the most comprehensive introductions to (and dissertations on) practical host-based networking I've ever seen. If you don't think you know everything you should about Linux networking (and who does?), it's worth checking out.
And if you have any suggestions or comments on the document, I can assure you that Martin is a very friendly person and would love to hear your opinion on it.