"Stopping and Restarting Apache," from the Apache documentation: http://httpd.apache.org/docs/stopping.html.
The Red Hat Package Manager web site: http://www.rpm.org/.
Maximum RPM, by Ed Bailey (Red Hat Press).
"RPM-HOWTO," by Donnie Barnes: http://www.rpm.org/support/RPM-HOWTO.html.
CVS (Concurrent Versions System) resources:
http://www.cvshome.org/ is the home of the CVS project and includes a plethora of documentation. Of special interest is the Cederqvist, the official CVS manual, available at http://www.cvshome.org/docs/manual/.
Open Source Development with CVS, by Karl Fogel (Coriolis, Inc.). Most of the book is available online at http://cvsbook.red-bean.com/.
CVS Quick Reference Card: http://www.refcards.com/about/cvs.html.
daemontools, a collection of tools for managing Unix services: http://cr.yp.to/daemontools.html.
Log collecting and processing tools: http://www.apache-tools.com/search.jsp?keys=log.
cronolog, a log file-rotation program for the Apache web server: http://www.cronolog.org/.
mod_log_spread, which provides reliable distributed logging for Apache http://www.backhand.org/mod_log_spread/.
Spread, a wide area group communication system: http://www.spread.org/.
Recall, an open source library for writing distributed, fault-tolerant, replicated storage servers. A Recall-based server will allow you to save and access data even in the presence of machine failures. See http://www.fault-tolerant.org/recall/.
Chapters 2, 4, 9, 11, and 28 in UNIX System Administration Handbook, by Evi Nemeth, Garth Snyder, Scott Seebass, and Trent H. Hein (Prentice Hall).
Chapters 4 and 5 in Optimizing UNIX for Performance, by Amir H. Majidimehr (Prentice Hall).
To learn more about memory management, refer to a book that deals with operating system theory, and especially with the operating systems used on web server machines.
A good starting point is one of the classic textbooks used in operating system courses. For example:
Operating System Concepts, by Abraham Silberschatz and Peter Baer Galvin (John Wiley & Sons, Inc.).
Applied Operating System Concepts, by Abraham Silberschatz, Peter Baer Galvin, and Greg Gagne (John Wiley & Sons, Inc.).
Design of the Unix Operating System, by Maurice Bach (Prentice Hall).
The Memory Management Reference at http://www.xanalys.com/software_tools/mm/ is also very helpful.
mod_backhand, which provides load balancing for Apache: http://www.backhand.org/mod_backhand/.
The High-Availability Linux Project, the definitive guide to load-balancing techniques: http://www.linux-ha.org/.
The Heartbeat project is a part of the HA Linux project.
lbnamed, a load-balancing name server written in Perl: http://www.stanford.edu/~riepel/lbnamed/ or http://www.stanford.edu/~schemers/docs/lbnamed/lbnamed.html.
"Network Address Translation and Networks: Virtual Servers (Load Balancing)": http://www.suse.de/~mha/linux-ip-nat/diplom/node4.html#SECTION00043100000000000000.
Linux Virtual Server Project: http://www.linuxvirtualserver.org/.
Linux and port forwarding: http://www.netfilter.org/ipchains/ or http://www.netfilter.org/.
"Efficient Support for P-HTTP in Cluster-Based Web Servers," by Mohit Aron and Willy Zwaenepoel, in Proceedings of the USENIX 1999 Annual Technical Conference, Monterey, CA, June 1999: http://www.cs.rice.edu/~druschel/usenix99lard.ps.gz or http://www.usenix.org/publications/library/proceedings/usenix99/full_papers/aron/aron_html/.
IP filter: http://coombs.anu.edu.au/~avalon/. The latest IP filter includes some simple load-balancing code that allows a round-robin distribution onto several machines via ipnat.
Perl modules available from http://www.modperl.com/book/source (not on CPAN):
Apache::BlockAgent, which allows you to block impolite web agents.
Apache::SpeedLimit, which allows you to limit indexing robots' speed.