A good Networking textbook. (Used in CSE 461).
An explaination of the Domain Name System.
A good introduction to HTTP that explains what really happens when you click on a link. And here's a more comprehensive tutorial.
A Technical Introduction to XML. Very good description of the XML specification. Describes tags, attributes, nesting, and DTDs. Mentions XSL only in passing.
The XML Bible (updated chapters)
A very brief overview with lots of pointers to related info.
XML gets down to business (NetWorker: The Craft of Network Computing, Sept 1999). Summary: high-level overview of XML and how it encodes semantics (as compared with HTML). Describes DTDs and how they constrain and define the tags and attributes usable within an XML document. Briefly covers the debate over XSL (as it competes with CSS and DOM). Mentions a few commerce-related applications of XML, such as micropayments and ads.
Data on the Web: From Relations to Semistructured Data and XML, by Serge Abiteboul, Peter Buneman, Dan Suciu, and Jim Gray.
XML Specification (W3C Recommendation)
XPointer Specification (W3C Working Draft) explains how to link between and into XML documents.
XSL Specification (W3C Working Draft) Explains how to use extensible stylesheets to specify 1) transformations between documents and 2) an XML vocabulary for specifying the formatting of XML documents.
Practical XML with Linux (CNN)
Nic Miloslav's Introduction to XML: a slew of XML/XSL examples walking you through the features of stylesheet transformations. It seems to cover more topics than the XML Bible, while being more accessible than the XSL specification.
Manageability, Availability and Performance in Porcupine: A Highly Scalable Internet Mail Service, by Yasushi Saito, Brian N. Bershad, and Henry M. Levy.
A Case for NOW, by Thomas E. Anderson, David E. Culler, David A. Patterson, and the NOW team.
White paper on java servlets (description of and introduction to servlet technology; not terribly readable)
There are many good commercial and free search engines. Some of them are listed on the Web Site Search Tools page. Open source search engines that are often used with Apache include ht://Dig and SWISH-E.
What order should a crawler use when following links?
The Ultimate Band Lista comprehensive resource.
On the scale and performance of cooperative Web proxy caching (more interesting, but harder and more specialized)